[input.output] - C++17 → C++20

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@@ -7,75 +7,74 @@ input/output operations.
 The following subclauses describe requirements for stream parameters,
 and components for forward declarations of iostreams, predefined
 iostreams objects, base iostreams classes, stream buffering, stream
 formatting and manipulators, string streams, and file streams, as
-summarized in Table  [[tab:iostreams.lib.summary]].
-**Table: Input/output library summary** <a id="tab:iostreams.lib.summary">[tab:iostreams.lib.summary]</a>
 | Subclause                  |                             | Header                                |
-| -------------------------- | --------------------------- | -------------- |
 | [[iostreams.requirements]] | Requirements                |                                       |
 | [[iostream.forward]]       | Forward declarations        | `<iosfwd>`                            |
 | [[iostream.objects]]       | Standard iostream objects   | `<iostream>`                          |
 | [[iostreams.base]]         | Iostreams base classes      | `<ios>`                               |
 | [[stream.buffers]]         | Stream buffers              | `<streambuf>`                         |
-| [[iostream.format]]        | Formatting and manipulators | `<istream>` |
-|                            |                             | `<ostream>`    |
-|                            |                             | `<iomanip>`    |
 | [[string.streams]]         | String streams              | `<sstream>`                           |
 | [[file.streams]]           | File streams                | `<fstream>`                           |
 | [[filesystems]]            | File systems                | `<filesystem>`                        |
-| [[c.files]]                | C library files             | `<cstdio>` |
-|                            |                             | `<cinttypes>`  |
-Figure  [[fig:streampos]] illustrates relationships among various types
-described in this clause. A line from **A** to **B** indicates that
-**A** is an alias (e.g. a typedef) for **B** or that **A** is defined in
-terms of **B**.
-<a id="fig:streampos"></a>
-![Stream position, offset, and size types \[non-normative\] \[fig:streampos\]](images/figstreampos.svg)
 ## Iostreams requirements <a id="iostreams.requirements">[[iostreams.requirements]]</a>
 ### Imbue limitations <a id="iostream.limits.imbue">[[iostream.limits.imbue]]</a>
-No function described in Clause  [[input.output]] except for
-`ios_base::imbue` and `basic_filebuf::pubimbue` causes any instance of
-`basic_ios::imbue` or `basic_streambuf::imbue` to be called. If any user
-function called from a function declared in Clause  [[input.output]] or
-as an overriding virtual function of any class declared in Clause
-[[input.output]] calls `imbue`, the behavior is undefined.
 ### Positioning type limitations <a id="iostreams.limits.pos">[[iostreams.limits.pos]]</a>
-The classes of Clause  [[input.output]] with template arguments `charT`
-and `traits` behave as described if `traits::pos_type` and
 `traits::off_type` are `streampos` and `streamoff` respectively. Except
 as noted explicitly below, their behavior when `traits::pos_type` and
 `traits::off_type` are other types is *implementation-defined*.
-In the classes of Clause  [[input.output]], a template parameter with
-name `charT` represents a member of the set of types containing `char`,
 `wchar_t`, and any other *implementation-defined* character types that
-satisfy the requirements for a character on which any of the iostream
 components can be instantiated.
 ### Thread safety <a id="iostreams.threadsafety">[[iostreams.threadsafety]]</a>
-Concurrent access to a stream object ([[string.streams]],
-[[file.streams]]), stream buffer object ([[stream.buffers]]), or C
-Library stream ([[c.files]]) by multiple threads may result in a data
-race ([[intro.multithread]]) unless otherwise specified (
-[[iostream.objects]]).
-[*Note 1*: Data races result in undefined behavior (
-[[intro.multithread]]). — *end note*]
 If one thread makes a library call *a* that writes a value to a stream
 and, as a result, another thread reads this value from the stream
 through a library call *b* such that this does not result in a data
 race, then *a*’s write synchronizes with *b*’s read.
@@ -84,15 +83,16 @@ race, then *a*’s write synchronizes with *b*’s read.
 ### Header `<iosfwd>` synopsis <a id="iosfwd.syn">[[iosfwd.syn]]</a>
 ``` cpp
 namespace std {
-  template<class charT> class char_traits;
-  template<> class char_traits<char>;
-  template<> class char_traits<char16_t>;
-  template<> class char_traits<char32_t>;
-  template<> class char_traits<wchar_t>;
   template<class T> class allocator;
   template<class charT, class traits = char_traits<charT>>
     class basic_ios;
@@ -125,10 +125,17 @@ namespace std {
   template<class charT, class traits = char_traits<charT>>
     class basic_ofstream;
   template<class charT, class traits = char_traits<charT>>
     class basic_fstream;
   template<class charT, class traits = char_traits<charT>>
     class istreambuf_iterator;
   template<class charT, class traits = char_traits<charT>>
     class ostreambuf_iterator;
@@ -148,10 +155,13 @@ namespace std {
   using filebuf  = basic_filebuf<char>;
   using ifstream = basic_ifstream<char>;
   using ofstream = basic_ofstream<char>;
   using fstream  = basic_fstream<char>;
   using wstreambuf = basic_streambuf<wchar_t>;
   using wistream   = basic_istream<wchar_t>;
   using wostream   = basic_ostream<wchar_t>;
   using wiostream  = basic_iostream<wchar_t>;
@@ -163,13 +173,19 @@ namespace std {
   using wfilebuf  = basic_filebuf<wchar_t>;
   using wifstream = basic_ifstream<wchar_t>;
   using wofstream = basic_ofstream<wchar_t>;
   using wfstream  = basic_fstream<wchar_t>;
   template<class state> class fpos;
   using streampos  = fpos<char_traits<char>::state_type>;
   using wstreampos = fpos<char_traits<wchar_t>::state_type>;
 }
 ```
 Default template arguments are described as appearing both in `<iosfwd>`
 and in the synopsis of other headers but it is well-formed to include
@@ -182,52 +198,42 @@ virtual base class for the class templates `basic_istream`,
 `basic_ostream`, and class templates derived from them. `basic_iostream`
 is a class template derived from both `basic_istream<charT, traits>` and
 `basic_ostream<charT, traits>`.
 The class template specialization `basic_streambuf<charT, traits>`
-serves as a base class for class templates `basic_stringbuf` and
-`basic_filebuf`.
 The class template specialization `basic_istream<charT, traits>` serves
 as a base class for class templates `basic_istringstream` and
 `basic_ifstream`.
 The class template specialization `basic_ostream<charT, traits>` serves
-as a base class for class templates `basic_ostringstream` and
-`basic_ofstream`.
 The class template specialization `basic_iostream<charT, traits>` serves
 as a base class for class templates `basic_stringstream` and
 `basic_fstream`.
 Other *typedef-name*s define instances of class templates specialized
 for `char` or `wchar_t` types.
 Specializations of the class template `fpos` are used for specifying
 file position information.
-The types `streampos` and `wstreampos` are used for positioning streams
-specialized on `char` and `wchar_t` respectively.
-[*Note 1*:
-This synopsis suggests a circularity between `streampos` and
 `char_traits<char>`. An implementation can avoid this circularity by
-substituting equivalent types. One way to do this might be
-``` cpp
-template<class stateT> class fpos { ... };      // depends on nothing
-using _STATE = ... ;             // implementation private declaration of stateT
-using streampos = fpos<_STATE>;
-template<> struct char_traits<char> {
-  using pos_type = streampos;
-}
-```
-— *end note*]
 ## Standard iostream objects <a id="iostream.objects">[[iostream.objects]]</a>
 ### Header `<iostream>` synopsis <a id="iostream.syn">[[iostream.syn]]</a>
@@ -251,115 +257,114 @@ namespace std {
 ```
 ### Overview <a id="iostream.objects.overview">[[iostream.objects.overview]]</a>
 In this Clause, the type name `FILE` refers to the type `FILE` declared
-in `<cstdio>` ([[cstdio.syn]]).
 The header `<iostream>` declares objects that associate objects with the
-standard C streams provided for by the functions declared in
-`<cstdio>` ([[c.files]]), and includes all the headers necessary to use
-these objects.
 The objects are constructed and the associations are established at some
 time prior to or during the first time an object of class
 `ios_base::Init` is constructed, and in any case before the body of
-`main` ([[basic.start.main]]) begins execution.[^2] The objects are not
 destroyed during program execution.[^3] The results of including
 `<iostream>` in a translation unit shall be as if `<iostream>` defined
 an instance of `ios_base::Init` with static storage duration.
 Mixing operations on corresponding wide- and narrow-character streams
 follows the same semantics as mixing such operations on `FILE`s, as
 specified in the C standard library.
-Concurrent access to a synchronized ([[ios.members.static]]) standard
-iostream object’s formatted and unformatted input ([[istream]]) and
-output ([[ostream]]) functions or a standard C stream by multiple
-threads shall not result in a data race ([[intro.multithread]]).
 [*Note 1*: Users must still synchronize concurrent use of these objects
 and streams by multiple threads if they wish to avoid interleaved
 characters. — *end note*]
- ISO C 7.21.2.
 ### Narrow stream objects <a id="narrow.stream.objects">[[narrow.stream.objects]]</a>
 ``` cpp
 istream cin;
 ```
 The object `cin` controls input from a stream buffer associated with the
-object `stdin`, declared in `<cstdio>` ([[cstdio.syn]]).
 After the object `cin` is initialized, `cin.tie()` returns `&cout`. Its
-state is otherwise the same as required for
-`basic_ios<char>::init` ([[basic.ios.cons]]).
 ``` cpp
 ostream cout;
 ```
 The object `cout` controls output to a stream buffer associated with the
-object `stdout`, declared in `<cstdio>` ([[cstdio.syn]]).
 ``` cpp
 ostream cerr;
 ```
 The object `cerr` controls output to a stream buffer associated with the
-object `stderr`, declared in `<cstdio>` ([[cstdio.syn]]).
 After the object `cerr` is initialized, `cerr.flags() & unitbuf` is
 nonzero and `cerr.tie()` returns `&cout`. Its state is otherwise the
-same as required for `basic_ios<char>::init` ([[basic.ios.cons]]).
 ``` cpp
 ostream clog;
 ```
 The object `clog` controls output to a stream buffer associated with the
-object `stderr`, declared in `<cstdio>` ([[cstdio.syn]]).
 ### Wide stream objects <a id="wide.stream.objects">[[wide.stream.objects]]</a>
 ``` cpp
 wistream wcin;
 ```
 The object `wcin` controls input from a stream buffer associated with
-the object `stdin`, declared in `<cstdio>` ([[cstdio.syn]]).
 After the object `wcin` is initialized, `wcin.tie()` returns `&wcout`.
 Its state is otherwise the same as required for
-`basic_ios<wchar_t>::init` ([[basic.ios.cons]]).
 ``` cpp
 wostream wcout;
 ```
 The object `wcout` controls output to a stream buffer associated with
-the object `stdout`, declared in `<cstdio>` ([[cstdio.syn]]).
 ``` cpp
 wostream wcerr;
 ```
 The object `wcerr` controls output to a stream buffer associated with
-the object `stderr`, declared in `<cstdio>` ([[cstdio.syn]]).
 After the object `wcerr` is initialized, `wcerr.flags() & unitbuf` is
 nonzero and `wcerr.tie()` returns `&wcout`. Its state is otherwise the
-same as required for `basic_ios<wchar_t>::init` ([[basic.ios.cons]]).
 ``` cpp
 wostream wclog;
 ```
 The object `wclog` controls output to a stream buffer associated with
-the object `stderr`, declared in `<cstdio>` ([[cstdio.syn]]).
 ## Iostreams base classes <a id="iostreams.base">[[iostreams.base]]</a>
 ### Header `<ios>` synopsis <a id="ios.syn">[[ios.syn]]</a>
@@ -449,11 +454,11 @@ an I/O operation, or the size of I/O buffers.[^5]
 namespace std {
   class ios_base {
   public:
     class failure;              // see below
-    // [ios::fmtflags], fmtflags
     using fmtflags = T1;
     static constexpr fmtflags boolalpha = unspecified;
     static constexpr fmtflags dec = unspecified;
     static constexpr fmtflags fixed = unspecified;
     static constexpr fmtflags hex = unspecified;
@@ -470,27 +475,27 @@ namespace std {
     static constexpr fmtflags uppercase = unspecified;
     static constexpr fmtflags adjustfield = see below;
     static constexpr fmtflags basefield = see below;
     static constexpr fmtflags floatfield = see below;
-    // [ios::iostate], iostate
     using iostate = T2;
     static constexpr iostate badbit = unspecified;
     static constexpr iostate eofbit = unspecified;
     static constexpr iostate failbit = unspecified;
     static constexpr iostate goodbit = see below;
-    // [ios::openmode], openmode
     using openmode = T3;
     static constexpr openmode app = unspecified;
     static constexpr openmode ate = unspecified;
     static constexpr openmode binary = unspecified;
     static constexpr openmode in = unspecified;
     static constexpr openmode out = unspecified;
     static constexpr openmode trunc = unspecified;
-    // [ios::seekdir], seekdir
     using seekdir = T4;
     static constexpr seekdir beg = unspecified;
     static constexpr seekdir cur = unspecified;
     static constexpr seekdir end = unspecified;
@@ -512,20 +517,20 @@ namespace std {
     locale imbue(const locale& loc);
     locale getloc() const;
     // [ios.base.storage], storage
     static int xalloc();
-    long&  iword(int index);
-    void*& pword(int index);
-    // destructor:
     virtual ~ios_base();
-    // [ios.base.callback], callbacks;
     enum event { erase_event, imbue_event, copyfmt_event };
-    using event_callback = void (*)(event, ios_base&, int index);
-    void register_callback(event_callback fn, int index);
     ios_base(const ios_base&) = delete;
     ios_base& operator=(const ios_base&) = delete;
     static bool sync_with_stdio(bool sync = true);
@@ -573,11 +578,11 @@ For the sake of exposition, the maintained data is presented here as:
 — *end note*]
 #### Types <a id="ios.types">[[ios.types]]</a>
-##### Class `ios_base::failure` <a id="ios::failure">[[ios::failure]]</a>
 ``` cpp
 namespace std {
   class ios_base::failure : public system_error {
   public:
@@ -589,13 +594,13 @@ namespace std {
 An implementation is permitted to define `ios_base::failure` as a
 synonym for a class with equivalent functionality to class
 `ios_base::failure` shown in this subclause.
-[*Note 1*: When `ios_base::failure` is a synonym for another type it
-shall provide a nested type `failure`, to emulate the injected class
-name. — *end note*]
 The class `failure` defines the base class for the types of all objects
 thrown as exceptions, by functions in the iostreams library, to report
 errors detected during stream buffer operations.
@@ -612,31 +617,28 @@ iostream_category())`. — *end note*]
 ``` cpp
 explicit failure(const string& msg, const error_code& ec = io_errc::stream);
 ```
-*Effects:* Constructs an object of class `failure` by constructing the
-base class with `msg` and `ec`.
 ``` cpp
 explicit failure(const char* msg, const error_code& ec = io_errc::stream);
 ```
-*Effects:* Constructs an object of class `failure` by constructing the
-base class with `msg` and `ec`.
-##### Type `ios_base::fmtflags` <a id="ios::fmtflags">[[ios::fmtflags]]</a>
 ``` cpp
 using fmtflags = T1;
 ```
-The type `fmtflags` is a bitmask type ([[bitmask.types]]). Setting its
-elements has the effects indicated in
-Table  [[tab:iostreams.fmtflags.effects]].
-**Table: `fmtflags` effects** <a id="tab:iostreams.fmtflags.effects">[tab:iostreams.fmtflags.effects]</a>
 | Element      | Effect(s) if set                                                                                                                        |
 | ------------ | --------------------------------------------------------------------------------------------------------------------------------------- |
 | `boolalpha`  | insert and extract `bool` type in alphabetic format                                                                                     |
 | `dec`        | converts integer input or generates integer output in decimal base                                                                      |
@@ -654,31 +656,31 @@ Table  [[tab:iostreams.fmtflags.effects]].
 | `unitbuf`    | flushes output after each output operation                                                                                              |
 | `uppercase`  | replaces certain lowercase letters with their uppercase equivalents in generated output                                                 |
 Type `fmtflags` also defines the constants indicated in
-Table  [[tab:iostreams.fmtflags.constants]].
-**Table: `fmtflags` constants** <a id="tab:iostreams.fmtflags.constants">[tab:iostreams.fmtflags.constants]</a>
 | Constant      | Allowable values          |
 | ------------- | ------------------------- |
 | `adjustfield` | `left | right | internal` |
 | `basefield`   | `dec | oct | hex`         |
 | `floatfield`  | `scientific | fixed`      |
-##### Type `ios_base::iostate` <a id="ios::iostate">[[ios::iostate]]</a>
 ``` cpp
 using iostate = T2;
 ```
-The type `iostate` is a bitmask type ([[bitmask.types]]) that contains
-the elements indicated in Table  [[tab:iostreams.iostate.effects]].
-**Table: `iostate` effects** <a id="tab:iostreams.iostate.effects">[tab:iostreams.iostate.effects]</a>
 | Element   | Effect(s) if set                                                                                                                                 |
 | --------- | ------------------------------------------------------------------------------------------------------------------------------------------------ |
 | `badbit`  | indicates a loss of integrity in an input or output sequence (such as an irrecoverable read error from a file);                                  |
 | `eofbit`  | indicates that an input operation reached the end of an input sequence;                                                                          |
@@ -687,20 +689,20 @@ the elements indicated in Table  [[tab:iostreams.iostate.effects]].
 Type `iostate` also defines the constant:
 - `goodbit`, the value zero.
-##### Type `ios_base::openmode` <a id="ios::openmode">[[ios::openmode]]</a>
 ``` cpp
 using openmode = T3;
 ```
-The type `openmode` is a bitmask type ([[bitmask.types]]). It contains
-the elements indicated in Table  [[tab:iostreams.openmode.effects]].
-**Table: `openmode` effects** <a id="tab:iostreams.openmode.effects">[tab:iostreams.openmode.effects]</a>
 | Element  | Effect(s) if set                                                  |
 | -------- | ----------------------------------------------------------------- |
 | `app`    | seek to end before each write                                     |
 | `ate`    | open and seek to end immediately after opening                    |
@@ -708,73 +710,71 @@ the elements indicated in Table  [[tab:iostreams.openmode.effects]].
 | `in`     | open for input                                                    |
 | `out`    | open for output                                                   |
 | `trunc`  | truncate an existing stream when opening                          |
-##### Type `ios_base::seekdir` <a id="ios::seekdir">[[ios::seekdir]]</a>
 ``` cpp
 using seekdir = T4;
 ```
-The type `seekdir` is an enumerated type ([[enumerated.types]]) that
-contains the elements indicated in
-Table  [[tab:iostreams.seekdir.effects]].
-**Table: `seekdir` effects** <a id="tab:iostreams.seekdir.effects">[tab:iostreams.seekdir.effects]</a>
 | Element | Meaning                                                                                 |
 | ------- | --------------------------------------------------------------------------------------- |
 | `beg`   | request a seek (for subsequent input or output) relative to the beginning of the stream |
 | `cur`   | request a seek relative to the current position within the sequence                     |
 | `end`   | request a seek relative to the current end of the sequence                              |
-##### Class `ios_base::Init` <a id="ios::Init">[[ios::Init]]</a>
 ``` cpp
 namespace std {
   class ios_base::Init {
   public:
     Init();
     ~Init();
   private:
     static int init_cnt;        // exposition only
   };
 }
 ```
 The class `Init` describes an object whose construction ensures the
-construction of the eight objects declared in `<iostream>` (
-[[iostream.objects]]) that associate file stream buffers with the
-standard C streams provided for by the functions declared in
-`<cstdio>` ([[cstdio.syn]]).
 For the sake of exposition, the maintained data is presented here as:
 - `static int init_cnt`, counts the number of constructor and destructor
   calls for class `Init`, initialized to zero.
 ``` cpp
 Init();
 ```
-*Effects:* Constructs an object of class `Init`. Constructs and
-initializes the objects `cin`, `cout`, `cerr`, `clog`, `wcin`, `wcout`,
-`wcerr`, and `wclog` if they have not already been constructed and
-initialized.
 ``` cpp
 ~Init();
 ```
-*Effects:* Destroys an object of class `Init`. If there are no other
-instances of the class still in existence, calls `cout.flush()`,
-`cerr.flush()`, `clog.flush()`, `wcout.flush()`, `wcerr.flush()`,
-`wclog.flush()`.
-#### `ios_base` state functions <a id="fmtflags.state">[[fmtflags.state]]</a>
 ``` cpp
 fmtflags flags() const;
 ```
@@ -782,11 +782,11 @@ fmtflags flags() const;
 ``` cpp
 fmtflags flags(fmtflags fmtfl);
 ```
-*Postconditions:* `fmtfl == flags()`.
 *Returns:* The previous value of `flags()`.
 ``` cpp
 fmtflags setf(fmtflags fmtfl);
@@ -818,11 +818,11 @@ streamsize precision() const;
 ``` cpp
 streamsize precision(streamsize prec);
 ```
-*Postconditions:* `prec == precision()`.
 *Returns:* The previous value of `precision()`.
 ``` cpp
 streamsize width() const;
@@ -833,47 +833,46 @@ certain output conversions.
 ``` cpp
 streamsize width(streamsize wide);
 ```
-*Postconditions:* `wide == width()`.
 *Returns:* The previous value of `width()`.
-#### `ios_base` functions <a id="ios.base.locales">[[ios.base.locales]]</a>
 ``` cpp
 locale imbue(const locale& loc);
 ```
-*Effects:* Calls each registered callback pair
-`(fn, index)` ([[ios.base.callback]]) as
-`(*fn)(imbue_event, *this, index)` at such a time that a call to
-`ios_base::getloc()` from within `fn` returns the new locale value
-`loc`.
 *Returns:* The previous value of `getloc()`.
-*Postconditions:* `loc == getloc()`.
 ``` cpp
 locale getloc() const;
 ```
-*Returns:* If no locale has been imbued, a copy of the global C++locale,
-`locale()`, in effect at the time of construction. Otherwise, returns
-the imbued locale, to be used to perform locale-dependent input and
-output operations.
-#### `ios_base` static members <a id="ios.members.static">[[ios.members.static]]</a>
 ``` cpp
-bool sync_with_stdio(bool sync = true);
 ```
 *Returns:* `true` if the previous state of the standard iostream
-objects ([[iostream.objects]]) was synchronized and otherwise returns
 `false`. The first time it is called, the function returns `true`.
 *Effects:* If any input or output operation has occurred using the
 standard streams prior to the call, the effect is
 *implementation-defined*. Otherwise, called with a `false` argument, it
@@ -919,25 +918,27 @@ is the same as the effect of
 str.rdbuf()->sputbackc(c);
 ```
 for any sequence of characters.[^6]
-#### `ios_base` storage functions <a id="ios.base.storage">[[ios.base.storage]]</a>
 ``` cpp
 static int xalloc();
 ```
 *Returns:* `index` `++`.
-*Remarks:* Concurrent access to this function by multiple threads shall
-not result in a data race ([[intro.multithread]]).
 ``` cpp
 long& iword(int idx);
 ```
 *Effects:* If `iarray` is a null pointer, allocates an array of `long`
 of unspecified size and stores a pointer to its first element in
 `iarray`. The function then extends the array pointed at by `iarray` as
 necessary to include the element `iarray[idx]`. Each newly allocated
 element of the array is initialized to zero. The reference returned is
@@ -954,10 +955,12 @@ initialized to 0.
 ``` cpp
 void*& pword(int idx);
 ```
 *Effects:* If `parray` is a null pointer, allocates an array of pointers
 to `void` of unspecified size and stores a pointer to its first element
 in `parray`. The function then extends the array pointed at by `parray`
 as necessary to include the element `parray[idx]`. Each newly allocated
 element of the array is initialized to a null pointer. The reference
@@ -973,29 +976,29 @@ object (which may throw `failure`).
 initialized to 0.
 *Remarks:* After a subsequent call to `pword(int)` for the same object,
 the earlier return value may no longer be valid.
-#### `ios_base` callbacks <a id="ios.base.callback">[[ios.base.callback]]</a>
 ``` cpp
-void register_callback(event_callback fn, int index);
 ```
-*Effects:* Registers the pair `(fn, index)` such that during calls to
-`imbue()` ([[ios.base.locales]]), `copyfmt()`, or
-`~ios_base()` ([[ios.base.cons]]), the function `fn` is called with
-argument `index`. Functions registered are called when an event occurs,
-in opposite order of registration. Functions registered while a callback
-function is active are not called until the next event.
-*Requires:* The function `fn` shall not throw exceptions.
 *Remarks:* Identical pairs are not merged. A function registered twice
 will be called twice.
-#### `ios_base` constructors/destructor <a id="ios.base.cons">[[ios.base.cons]]</a>
 ``` cpp
 ios_base();
 ```
@@ -1006,14 +1009,14 @@ destroyed, whichever comes first; otherwise the behavior is undefined.
 ``` cpp
 ~ios_base();
 ```
-*Effects:* Destroys an object of class `ios_base`. Calls each registered
-callback pair `(fn, index)` ([[ios.base.callback]]) as
-`(*fn)(erase_event, *this, index)` at such time that any `ios_base`
-member function called from within `fn` has well defined results.
 ### Class template `fpos` <a id="fpos">[[fpos]]</a>
 ``` cpp
 namespace std {
@@ -1026,11 +1029,11 @@ namespace std {
     stateT st;                  // exposition only
   };
 }
 ```
-#### `fpos` members <a id="fpos.members">[[fpos.members]]</a>
 ``` cpp
 void state(stateT s);
 ```
@@ -1040,27 +1043,36 @@ void state(stateT s);
 stateT state() const;
 ```
 *Returns:* Current value of `st`.
-#### `fpos` requirements <a id="fpos.operations">[[fpos.operations]]</a>
-Operations specified in Table  [[tab:iostreams.position.requirements]]
-are permitted. In that table,
 - `P` refers to an instance of `fpos`,
-- `p` and `q` refer to values of type `P`,
-- `O` refers to type `streamoff`,
-- `o` refers to a value of type `streamoff`,
-- `sz` refers to a value of type `streamsize` and
-- `i` refers to a value of type `int`.
-[*Note 1*: Every implementation is required to supply overloaded
-operators on `fpos` objects to satisfy the requirements of
-[[fpos.operations]]. It is unspecified whether these operators are
-members of `fpos`, global operators, or provided in some other
-way. — *end note*]
 Stream operations that return a value of type `traits::pos_type` return
 `P(O(-1))` as an invalid value to signal an error. If this value is used
 as an argument to any `istream`, `ostream`, or `streambuf` member that
 accepts a value of type `traits::pos_type` then the behavior of that
@@ -1129,28 +1141,27 @@ namespace std {
   };
 }
 ```
-#### `basic_ios` constructors <a id="basic.ios.cons">[[basic.ios.cons]]</a>
 ``` cpp
 explicit basic_ios(basic_streambuf<charT, traits>* sb);
 ```
-*Effects:* Constructs an object of class `basic_ios`, assigning initial
-values to its member objects by calling `init(sb)`.
 ``` cpp
 basic_ios();
 ```
-*Effects:* Constructs an object of class
-`basic_ios` ([[ios.base.cons]]) leaving its member objects
-uninitialized. The object shall be initialized by calling
-`basic_ios::init` before its first use or before it is destroyed,
-whichever comes first; otherwise the behavior is undefined.
 ``` cpp
 ~basic_ios();
 ```
@@ -1158,14 +1169,14 @@ whichever comes first; otherwise the behavior is undefined.
 ``` cpp
 void init(basic_streambuf<charT, traits>* sb);
 ```
-*Postconditions:* The postconditions of this function are indicated in
-Table  [[tab:iostreams.basicios.init.effects]].
-**Table: `basic_ios::init()` effects** <a id="tab:iostreams.basicios.init.effects">[tab:iostreams.basicios.init.effects]</a>
 | Element        | Value                                                        |
 | -------------- | ------------------------------------------------------------ |
 | `rdbuf()`      | `sb`                                                         |
 | `tie()`        | `0`                                                          |
@@ -1191,15 +1202,15 @@ sequence controlled by the stream buffer.
 ``` cpp
 basic_ostream<charT, traits>* tie(basic_ostream<charT, traits>* tiestr);
 ```
-*Requires:* If `tiestr` is not null, `tiestr` must not be reachable by
 traversing the linked list of tied stream objects starting from
 `tiestr->tie()`.
-*Postconditions:* `tiestr == tie()`.
 *Returns:* The previous value of `tie()`.
 ``` cpp
 basic_streambuf<charT, traits>* rdbuf() const;
@@ -1209,22 +1220,22 @@ basic_streambuf<charT, traits>* rdbuf() const;
 ``` cpp
 basic_streambuf<charT, traits>* rdbuf(basic_streambuf<charT, traits>* sb);
 ```
-*Postconditions:* `sb == rdbuf()`.
 *Effects:* Calls `clear()`.
 *Returns:* The previous value of `rdbuf()`.
 ``` cpp
 locale imbue(const locale& loc);
 ```
-*Effects:* Calls `ios_base::imbue(loc)` ([[ios.base.locales]]) and if
-`rdbuf() != 0` then `rdbuf()->pubimbue(loc)` ([[streambuf.locales]]).
 *Returns:* The prior value of `ios_base::imbue()`.
 ``` cpp
 char narrow(char_type c, char dfault) const;
@@ -1247,45 +1258,45 @@ specified field width.
 ``` cpp
 char_type fill(char_type fillch);
 ```
-*Postconditions:* `traits::eq(fillch, fill())`.
 *Returns:* The previous value of `fill()`.
 ``` cpp
 basic_ios& copyfmt(const basic_ios& rhs);
 ```
-*Effects:* If `(this == &rhs)` does nothing. Otherwise assigns to the
-member objects of `*this` the corresponding member objects of `rhs` as
-follows:
-1.  calls each registered callback pair `(fn, index)` as
- `(*fn)(erase_event, *this, index)`;
-2.  assigns to the member objects of `*this` the corresponding member
- objects of `rhs`, except that
   - `rdstate()`, `rdbuf()`, and `exceptions()` are left unchanged;
- - the contents of arrays pointed at by `pword` and `iword` are
-      copied, not the pointers themselves;[^10] and
   - if any newly stored pointer values in `*this` point at objects
- stored outside the object `rhs` and those objects are destroyed
-      when `rhs` is destroyed, the newly stored pointer values are
-      altered to point at newly constructed copies of the objects;
-3.  calls each callback pair that was copied from `rhs` as
- `(*fn)(copyfmt_event, *this, index)`;
-4.  calls `exceptions(rhs.exceptions())`.
 [*Note 1*: The second pass through the callback pairs permits a copied
 `pword` value to be zeroed, or to have its referent deep copied or
 reference counted, or to have other special action taken. — *end note*]
-*Postconditions:* The postconditions of this function are indicated in
-Table  [[tab:iostreams.copyfmt.effects]].
-**Table: `basic_ios::copyfmt()` effects** <a id="tab:iostreams.copyfmt.effects">[tab:iostreams.copyfmt.effects]</a>
 | Element        | Value              |
 | -------------- | ------------------ |
 | `rdbuf()`      | unchanged          |
 | `tie()`        | `rhs.tie()`        |
@@ -1303,39 +1314,38 @@ Table  [[tab:iostreams.copyfmt.effects]].
 ``` cpp
 void move(basic_ios& rhs);
 void move(basic_ios&& rhs);
 ```
-*Postconditions:* `*this` shall have the state that `rhs` had before the
-function call, except that `rdbuf()` shall return 0. `rhs` shall be in a
-valid but unspecified state, except that `rhs.rdbuf()` shall return the
-same value as it returned before the function call, and `rhs.tie()`
-shall return 0.
 ``` cpp
 void swap(basic_ios& rhs) noexcept;
 ```
-*Effects:* The states of `*this` and `rhs` shall be exchanged, except
-that `rdbuf()` shall return the same value as it returned before the
-function call, and `rhs.rdbuf()` shall return the same value as it
-returned before the function call.
 ``` cpp
 void set_rdbuf(basic_streambuf<charT, traits>* sb);
 ```
-*Requires:* `sb != nullptr`.
 *Effects:* Associates the `basic_streambuf` object pointed to by `sb`
 with this stream without calling `clear()`.
-*Postconditions:* `rdbuf() == sb`.
 *Throws:* Nothing.
-#### `basic_ios` flags functions <a id="iostate.flags">[[iostate.flags]]</a>
 ``` cpp
 explicit operator bool() const;
 ```
@@ -1355,25 +1365,25 @@ iostate rdstate() const;
 ``` cpp
 void clear(iostate state = goodbit);
 ```
-*Postconditions:* If `rdbuf() != 0` then `state == rdstate()`; otherwise
 `rdstate() == (state | ios_base::badbit)`.
 *Effects:* If
 `((state | (rdbuf() ? goodbit : badbit)) & exceptions()) == 0`, returns.
-Otherwise, the function throws an object of class
-`basic_ios::failure` ([[ios::failure]]), constructed with
-*implementation-defined* argument values.
 ``` cpp
 void setstate(iostate state);
 ```
 *Effects:* Calls `clear(rdstate() | state)` (which may throw
-`basic_ios::failure` ([[ios::failure]])).
 ``` cpp
 bool good() const;
 ```
@@ -1406,18 +1416,21 @@ exceptions to be thrown.
 ``` cpp
 void exceptions(iostate except);
 ```
-*Postconditions:* `except == exceptions()`.
 *Effects:* Calls `clear(rdstate())`.
 ### `ios_base` manipulators <a id="std.ios.manip">[[std.ios.manip]]</a>
 #### `fmtflags` manipulators <a id="fmtflags.manip">[[fmtflags.manip]]</a>
 ``` cpp
 ios_base& boolalpha(ios_base& str);
 ```
 *Effects:* Calls `str.setf(ios_base::boolalpha)`.
@@ -1528,10 +1541,13 @@ ios_base& nounitbuf(ios_base& str);
 *Returns:* `str`.
 #### `adjustfield` manipulators <a id="adjustfield.manip">[[adjustfield.manip]]</a>
 ``` cpp
 ios_base& internal(ios_base& str);
 ```
 *Effects:* Calls `str.setf(ios_base::internal, ios_base::adjustfield)`.
@@ -1554,10 +1570,13 @@ ios_base& right(ios_base& str);
 *Returns:* `str`.
 #### `basefield` manipulators <a id="basefield.manip">[[basefield.manip]]</a>
 ``` cpp
 ios_base& dec(ios_base& str);
 ```
 *Effects:* Calls `str.setf(ios_base::dec, ios_base::basefield)`.
@@ -1580,10 +1599,13 @@ ios_base& oct(ios_base& str);
 *Returns:* `str`.
 #### `floatfield` manipulators <a id="floatfield.manip">[[floatfield.manip]]</a>
 ``` cpp
 ios_base& fixed(ios_base& str);
 ```
 *Effects:* Calls `str.setf(ios_base::fixed, ios_base::floatfield)`.
@@ -1607,22 +1629,22 @@ ios_base& hexfloat(ios_base& str);
 *Returns:* `str`.
 [*Note 1*: The more obvious use of `ios_base::hex` to specify
 hexadecimal floating-point format would change the meaning of existing
-well defined programs. C++03 gives no meaning to the combination of
 `fixed` and `scientific`. — *end note*]
 ``` cpp
 ios_base& defaultfloat(ios_base& str);
 ```
 *Effects:* Calls `str.unsetf(ios_base::floatfield)`.
 *Returns:* `str`.
-#### Error reporting <a id="error.reporting">[[error.reporting]]</a>
 ``` cpp
 error_code make_error_code(io_errc e) noexcept;
 ```
@@ -1740,11 +1762,11 @@ namespace std {
     pos_type pubseekpos(pos_type sp,
                         ios_base::openmode which
                           = ios_base::in | ios_base::out);
     int      pubsync();
-    // Get and put areas
     // [streambuf.pub.get], get area
     streamsize in_avail();
     int_type snextc();
     int_type sbumpc();
     int_type sgetc();
@@ -1814,20 +1836,19 @@ for deriving various *stream buffers* whose objects each control two
 *character sequences*:
 - a character *input sequence*;
 - a character *output sequence*.
-#### `basic_streambuf` constructors <a id="streambuf.cons">[[streambuf.cons]]</a>
 ``` cpp
 basic_streambuf();
 ```
-*Effects:* Constructs an object of class
-`basic_streambuf<charT, traits>` and initializes:[^13]
-- all its pointer member objects to null pointers,
 - the `getloc()` member to a copy the global locale, `locale()`, at the
   time of construction.
 *Remarks:* Once the `getloc()` member is initialized, results of calling
 locale member functions, and of members of facets so obtained, can
@@ -1835,13 +1856,11 @@ safely be cached until the next time the member `imbue` is called.
 ``` cpp
 basic_streambuf(const basic_streambuf& rhs);
 ```
-*Effects:* Constructs a copy of `rhs`.
-*Postconditions:*
 - `eback() == rhs.eback()`
 - `gptr() == rhs.gptr()`
 - `egptr() == rhs.egptr()`
 - `pbase() == rhs.pbase()`
@@ -1853,22 +1872,22 @@ basic_streambuf(const basic_streambuf& rhs);
 ~basic_streambuf();
 ```
 *Effects:* None.
-#### `basic_streambuf` public member functions <a id="streambuf.members">[[streambuf.members]]</a>
 ##### Locales <a id="streambuf.locales">[[streambuf.locales]]</a>
 ``` cpp
 locale pubimbue(const locale& loc);
 ```
-*Postconditions:* `loc == getloc()`.
 *Effects:* Calls `imbue(loc)`.
 *Returns:* Previous value of `getloc()`.
 ``` cpp
 locale getloc() const;
 ```
@@ -1914,11 +1933,11 @@ int pubsync();
 ``` cpp
 streamsize in_avail();
 ```
 *Returns:* If a read position is available, returns `egptr() - gptr()`.
-Otherwise returns `showmanyc()` ([[streambuf.virt.get]]).
 ``` cpp
 int_type snextc();
 ```
@@ -1929,11 +1948,11 @@ int_type snextc();
 ``` cpp
 int_type sbumpc();
 ```
-*Returns:* If the input sequence read position is not available, returns
 `uflow()`. Otherwise, returns `traits::to_int_type(*gptr())` and
 increments the next pointer for the input sequence.
 ``` cpp
 int_type sgetc();
@@ -1952,52 +1971,50 @@ streamsize sgetn(char_type* s, streamsize n);
 ``` cpp
 int_type sputbackc(char_type c);
 ```
-*Returns:* If the input sequence putback position is not available, or
 if `traits::eq(c, gptr()[-1])` is `false`, returns
 `pbackfail(traits::to_int_type(c))`. Otherwise, decrements the next
 pointer for the input sequence and returns
 `traits::to_int_type(*gptr())`.
 ``` cpp
 int_type sungetc();
 ```
-*Returns:* If the input sequence putback position is not available,
 returns `pbackfail()`. Otherwise, decrements the next pointer for the
 input sequence and returns `traits::to_int_type(*gptr())`.
 ##### Put area <a id="streambuf.pub.put">[[streambuf.pub.put]]</a>
 ``` cpp
 int_type sputc(char_type c);
 ```
-*Returns:* If the output sequence write position is not available,
 returns `overflow(traits::to_int_type(c))`. Otherwise, stores `c` at the
 next pointer for the output sequence, increments the pointer, and
 returns `traits::to_int_type(c)`.
 ``` cpp
 streamsize sputn(const char_type* s, streamsize n);
 ```
 *Returns:* `xsputn(s, n)`.
-#### `basic_streambuf` protected member functions <a id="streambuf.protected">[[streambuf.protected]]</a>
 ##### Assignment <a id="streambuf.assign">[[streambuf.assign]]</a>
 ``` cpp
 basic_streambuf& operator=(const basic_streambuf& rhs);
 ```
-*Effects:* Assigns the data members of `rhs` to `*this`.
-*Postconditions:*
 - `eback() == rhs.eback()`
 - `gptr() == rhs.gptr()`
 - `egptr() == rhs.egptr()`
 - `pbase() == rhs.pbase()`
@@ -2041,12 +2058,12 @@ void gbump(int n);
 ``` cpp
 void setg(char_type* gbeg, char_type* gnext, char_type* gend);
 ```
-*Postconditions:* `gbeg == eback()`, `gnext == gptr()`, and
-`gend == egptr()`.
 ##### Put area access <a id="streambuf.put.area">[[streambuf.put.area]]</a>
 ``` cpp
 char_type* pbase() const;
@@ -2074,14 +2091,14 @@ void pbump(int n);
 ``` cpp
 void setp(char_type* pbeg, char_type* pend);
 ```
-*Postconditions:* `pbeg == pbase()`, `pbeg == pptr()`, and
-`pend == epptr()`.
-#### `basic_streambuf` virtual functions <a id="streambuf.virtuals">[[streambuf.virtuals]]</a>
 ##### Locales <a id="streambuf.virt.locales">[[streambuf.virt.locales]]</a>
 ``` cpp
 void imbue(const locale&);
@@ -2142,11 +2159,11 @@ int sync();
 is, if `pbase()` is non-null the characters between `pbase()` and
 `pptr()` are written to the controlled sequence. The pointers may then
 be reset as appropriate.
 *Returns:* `-1` on failure. What constitutes failure is determined by
-each derived class ([[filebuf.virtuals]]).
 *Default behavior:* Returns zero.
 ##### Get area <a id="streambuf.virt.get">[[streambuf.virt.get]]</a>
@@ -2183,11 +2200,11 @@ to `sbumpc()` would return `traits::eof()`.
 ``` cpp
 int_type underflow();
 ```
 *Remarks:* The public members of `basic_streambuf` call this virtual
-function only if `gptr()` is null or `gptr() >= egptr()`
 *Returns:* `traits::to_int_type(c)`, where `c` is the first *character*
 of the *pending sequence*, without moving the input sequence position
 past it. If the pending sequence is null then the function returns
 `traits::eof()` to indicate failure.
@@ -2225,13 +2242,13 @@ that either
 ``` cpp
 int_type uflow();
 ```
-*Requires:* The constraints are the same as for `underflow()`, except
-that the result character shall be transferred from the pending sequence
-to the backup sequence, and the pending sequence shall not be empty
 before the transfer.
 *Default behavior:* Calls `underflow()`. If `underflow()` returns
 `traits::eof()`, returns `traits::eof()`. Otherwise, returns the value
 of `traits::to_int_type(*gptr())` and increment the value of the next
@@ -2258,11 +2275,11 @@ modifications that
   is determined.
 - If `traits::eq_int_type(c, traits::eof())` returns `false`, then `c`
   is prepended. Whether the input sequence is backed up or modified in
   any other way is unspecified.
-*Postconditions:* On return, the constraints of `gptr()`, `eback()`, and
 `pptr()` are the same as for `underflow()`.
 *Returns:* `traits::eof()` to indicate failure. Failure may occur
 because the input sequence could not be backed up, or if for some other
 reason the pointers could not be set consistent with the constraints.
@@ -2294,32 +2311,32 @@ int_type overflow(int_type c = traits::eof());
 *Effects:* Consumes some initial subsequence of the characters of the
 *pending sequence*. The pending sequence is defined as the concatenation
 of
-- the empty sequence if `pbase()` is not null, otherwise the
   `pptr() - pbase()` characters beginning at `pbase()`, followed by
 - the empty sequence if `traits::eq_int_type(c, traits::eof())` returns
   `true`, otherwise the sequence consisting of `c`.
 *Remarks:* The member functions `sputc()` and `sputn()` call this
 function in case that no room can be found in the put buffer enough to
 accommodate the argument character sequence.
-*Requires:* Every overriding definition of this virtual function shall
-obey the following constraints:
-1.  The effect of consuming a character on the associated output
-    sequence is specified[^16]
-2.  Let `r` be the number of characters in the pending sequence not
- consumed. If `r` is nonzero then `pbase()` and `pptr()` shall be set
-    so that: `pptr() - pbase() == r` and the `r` characters starting at
   `pbase()` are the associated output stream. In case `r` is zero (all
   characters of the pending sequence have been consumed) then either
- `pbase()` is set to `nullptr`, or `pbase()` and `pptr()` are both
-    set to the same non-null value.
-3.  The function may fail if either appending some character to the
   associated output stream fails or if it is unable to establish
   `pbase()` and `pptr()` according to the above rules.
 *Returns:* `traits::eof()` or throws an exception if the function fails.
@@ -2369,10 +2386,17 @@ namespace std {
   template<class charT, class traits>
     basic_ostream<charT, traits>& ends(basic_ostream<charT, traits>& os);
   template<class charT, class traits>
     basic_ostream<charT, traits>& flush(basic_ostream<charT, traits>& os);
   template<class charT, class traits, class T>
     basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>&& os, const T& x);
 }
 ```
@@ -2382,11 +2406,11 @@ namespace std {
 namespace std {
   // types T1, T2, ... are unspecified implementation types
   T1 resetiosflags(ios_base::fmtflags mask);
   T2 setiosflags  (ios_base::fmtflags mask);
   T3 setbase(int base);
-  template<charT> T4 setfill(charT c);
   T5 setprecision(int n);
   T6 setw(int n);
   template<class moneyT> T7 get_money(moneyT& mon, bool intl = false);
   template<class moneyT> T8 put_money(const moneyT& mon, bool intl = false);
   template<class charT> T9 get_time(struct tm* tmb, const charT* fmt);
@@ -2420,22 +2444,22 @@ extracts from stream rvalues.
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
   class basic_istream : virtual public basic_ios<charT, traits> {
   public:
-    // types (inherited from basic_ios ([ios])):
     using char_type   = charT;
     using int_type    = typename traits::int_type;
     using pos_type    = typename traits::pos_type;
     using off_type    = typename traits::off_type;
     using traits_type = traits;
     // [istream.cons], constructor/destructor
     explicit basic_istream(basic_streambuf<charT, traits>* sb);
     virtual ~basic_istream();
-    // [istream::sentry], prefix/suffix
     class sentry;
     // [istream.formatted], formatted input
     basic_istream<charT, traits>&
       operator>>(basic_istream<charT, traits>& (*pf)(basic_istream<charT, traits>&));
@@ -2485,15 +2509,15 @@ namespace std {
     basic_istream<charT, traits>& seekg(pos_type);
     basic_istream<charT, traits>& seekg(off_type, ios_base::seekdir);
   protected:
     // [istream.cons], copy/move constructor
-    basic_istream(const basic_istream& rhs) = delete;
     basic_istream(basic_istream&& rhs);
     // [istream.assign], assign and swap
-    basic_istream& operator=(const basic_istream& rhs) = delete;
     basic_istream& operator=(basic_istream&& rhs);
     void swap(basic_istream& rhs);
   };
   // [istream.extractors], character extraction templates
@@ -2502,16 +2526,16 @@ namespace std {
   template<class traits>
     basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, unsigned char&);
   template<class traits>
     basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, signed char&);
-  template<class charT, class traits>
-    basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>&, charT*);
-  template<class traits>
-    basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, unsigned char*);
-  template<class traits>
-    basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, signed char*);
 }
 ```
 The class template `basic_istream` defines a number of member function
 signatures that assist in reading and interpreting input from sequences
@@ -2524,72 +2548,67 @@ obtain (or *extract*) input *characters* by calling `rdbuf()->sbumpc()`
 or `rdbuf()->sgetc()`. They may use other public members of `istream`.
 If `rdbuf()->sbumpc()` or `rdbuf()->sgetc()` returns `traits::eof()`,
 then the input function, except as explicitly noted otherwise, completes
 its actions and does `setstate(eofbit)`, which may throw
-`ios_base::failure` ([[iostate.flags]]), before returning.
 If one of these called functions throws an exception, then unless
-explicitly noted otherwise, the input function sets `badbit` in error
-state. If `badbit` is on in `exceptions()`, the input function rethrows
-the exception without completing its actions, otherwise it does not
-throw anything and proceeds as if the called function had returned a
 failure indication.
-##### `basic_istream` constructors <a id="istream.cons">[[istream.cons]]</a>
 ``` cpp
 explicit basic_istream(basic_streambuf<charT, traits>* sb);
 ```
-*Effects:* Constructs an object of class `basic_istream`, initializing
-the base class subobject with
-`basic_ios::init(sb)` ([[basic.ios.cons]]).
-*Postconditions:* `gcount() == 0`.
 ``` cpp
 basic_istream(basic_istream&& rhs);
 ```
-*Effects:* Move constructs from the rvalue `rhs`. This is accomplished
-by default constructing the base class, copying the `gcount()` from
-`rhs`, calling `basic_ios<charT, traits>::move(rhs)` to initialize the
-base class, and setting the `gcount()` for `rhs` to 0.
 ``` cpp
 virtual ~basic_istream();
 ```
-*Effects:* Destroys an object of class `basic_istream`.
 *Remarks:* Does not perform any operations of `rdbuf()`.
-##### Class `basic_istream` assign and swap <a id="istream.assign">[[istream.assign]]</a>
 ``` cpp
 basic_istream& operator=(basic_istream&& rhs);
 ```
-*Effects:* As if by `swap(rhs)`.
 *Returns:* `*this`.
 ``` cpp
 void swap(basic_istream& rhs);
 ```
 *Effects:* Calls `basic_ios<charT, traits>::swap(rhs)`. Exchanges the
 values returned by `gcount()` and `rhs.gcount()`.
-##### Class `basic_istream::sentry` <a id="istream::sentry">[[istream::sentry]]</a>
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
   class basic_istream<charT, traits>::sentry {
-    using traits_type = traits;
     bool ok_;                   // exposition only
   public:
     explicit sentry(basic_istream<charT, traits>& is, bool noskipws = false);
     ~sentry();
     explicit operator bool() const { return ok_; }
@@ -2640,11 +2659,11 @@ if (ctype.is(ctype.space, c) != 0)
 ```
 If, after any preparation is completed, `is.good()` is `true`,
 `ok_ != false` otherwise, `ok_ == false`. During preparation, the
 constructor may call `setstate(failbit)` (which may throw
-`ios_base::failure` ([[iostate.flags]]))[^19]
 ``` cpp
 ~sentry();
 ```
@@ -2652,23 +2671,23 @@ constructor may call `setstate(failbit)` (which may throw
 ``` cpp
 explicit operator bool() const;
 ```
-*Effects:* Returns `ok_`.
 #### Formatted input functions <a id="istream.formatted">[[istream.formatted]]</a>
 ##### Common requirements <a id="istream.formatted.reqmts">[[istream.formatted.reqmts]]</a>
 Each formatted input function begins execution by constructing an object
 of class `sentry` with the `noskipws` (second) argument `false`. If the
 `sentry` object returns `true`, when converted to a value of type
 `bool`, the function endeavors to obtain the requested input. If an
-exception is thrown during input then `ios::badbit` is turned on[^20] in
-`*this`’s error state. If `(exceptions()&badbit) != 0` then the
-exception is rethrown. In any case, the formatted input function
 destroys the `sentry` object. If no exception has been thrown, it
 returns `*this`.
 ##### Arithmetic extractors <a id="istream.formatted.arithmetic">[[istream.formatted.arithmetic]]</a>
@@ -2685,11 +2704,11 @@ operator>>(long double& val);
 operator>>(bool& val);
 operator>>(void*& val);
 ```
 As in the case of the inserters, these extractors depend on the locale’s
-`num_get<>` ([[locale.num.get]]) object to perform parsing the input
 stream data. These extractors behave as formatted input functions (as
 described in  [[istream.formatted.reqmts]]). After a sentry object is
 constructed, the conversion occurs as if performed by the following code
 fragment:
@@ -2789,26 +2808,23 @@ formatted input function (as described
 in  [[istream.formatted.reqmts]]).
 *Returns:* `*this`.
 ``` cpp
-template<class charT, class traits>
-  basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>& in, charT* s);
-template<class traits>
-  basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, unsigned char* s);
-template<class traits>
-  basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, signed char* s);
 ```
 *Effects:* Behaves like a formatted input member (as described
 in  [[istream.formatted.reqmts]]) of `in`. After a `sentry` object is
-constructed, `operator>>` extracts characters and stores them into
-successive locations of an array whose first element is designated by
-`s`. If `width()` is greater than zero, `n` is `width()`. Otherwise `n`
-is the number of elements of the largest array of `char_type` that can
-store a terminating `charT()`. `n` is the maximum number of characters
-stored.
 Characters are extracted and stored until any of the following occurs:
 - `n-1` characters are stored;
 - end of file occurs on the input sequence;
@@ -2818,11 +2834,11 @@ Characters are extracted and stored until any of the following occurs:
 `operator>>` then stores a null byte (`charT()`) in the next position,
 which may be the first position if no characters were extracted.
 `operator>>` then calls `width(0)`.
 If the function extracted no characters, it calls `setstate(failbit)`,
-which may throw `ios_base::failure` ([[iostate.flags]]).
 *Returns:* `in`.
 ``` cpp
 template<class charT, class traits>
@@ -2842,28 +2858,28 @@ stored in `c`. Otherwise, the function calls `in.setstate(failbit)`.
 ``` cpp
 basic_istream<charT, traits>& operator>>(basic_streambuf<charT, traits>* sb);
 ```
-*Effects:* Behaves as an unformatted input function
-([[istream.unformatted]]). If `sb` is null, calls `setstate(failbit)`,
-which may throw `ios_base::failure` ([[iostate.flags]]). After a sentry
-object is constructed, extracts characters from `*this` and inserts them
-in the output sequence controlled by `sb`. Characters are extracted and
-inserted until any of the following occurs:
 - end-of-file occurs on the input sequence;
 - inserting in the output sequence fails (in which case the character to
   be inserted is not extracted);
 - an exception occurs (in which case the exception is caught).
 If the function inserts no characters, it calls `setstate(failbit)`,
-which may throw `ios_base::failure` ([[iostate.flags]]). If it inserted
-no characters because it caught an exception thrown while extracting
-characters from `*this` and `failbit` is on in
-`exceptions()` ([[iostate.flags]]), then the caught exception is
-rethrown.
 *Returns:* `*this`.
 #### Unformatted input functions <a id="istream.unformatted">[[istream.unformatted]]</a>
@@ -2876,14 +2892,14 @@ an exception or if the sentry object returns `false`, when converted to
 a value of type `bool`, the function returns without attempting to
 obtain any input. In either case the number of extracted characters is
 set to 0; unformatted input functions taking a character array of
 nonzero size as an argument shall also store a null character (using
 `charT()`) in the first location of the array. If an exception is thrown
-during input then `ios::badbit` is turned on[^23] in `*this`’s error
-state. (Exceptions thrown from `basic_ios<>::clear()` are not caught or
-rethrown.) If `(exceptions()&badbit) != 0` then the exception is
-rethrown. It also counts the number of characters extracted. If no
 exception has been thrown it ends by storing the count in a member
 object and returning the value specified. In any event the `sentry`
 object is destroyed before leaving the unformatted input function.
 ``` cpp
@@ -2901,23 +2917,23 @@ int_type get();
 ```
 *Effects:* Behaves as an unformatted input function (as described
 above). After constructing a sentry object, extracts a character `c`, if
 one is available. Otherwise, the function calls `setstate(failbit)`,
-which may throw `ios_base::failure` ([[iostate.flags]]),
 *Returns:* `c` if available, otherwise `traits::eof()`.
 ``` cpp
 basic_istream<charT, traits>& get(char_type& c);
 ```
 *Effects:* Behaves as an unformatted input function (as described
 above). After constructing a sentry object, extracts a character, if one
 is available, and assigns it to `c`.[^24] Otherwise, the function calls
-`setstate(failbit)` (which may throw
-`ios_base::failure` ([[iostate.flags]])).
 *Returns:* `*this`.
 ``` cpp
 basic_istream<charT, traits>& get(char_type* s, streamsize n, char_type delim);
@@ -2934,13 +2950,13 @@ the following occurs:
   calls `setstate(eofbit)`);
 - `traits::eq(c, delim)` for the next available input character `c` (in
   which case `c` is not extracted).
 If the function stores no characters, it calls `setstate(failbit)`
-(which may throw `ios_base::failure` ([[iostate.flags]])). In any case,
-if `n` is greater than zero it then stores a null character into the
-next successive location of the array.
 *Returns:* `*this`.
 ``` cpp
 basic_istream<charT, traits>& get(char_type* s, streamsize n);
@@ -2966,11 +2982,11 @@ extracted and inserted until any of the following occurs:
   which case `c` is not extracted);
 - an exception occurs (in which case, the exception is caught but not
   rethrown).
 If the function inserts no characters, it calls `setstate(failbit)`,
-which may throw `ios_base::failure` ([[iostate.flags]]).
 *Returns:* `*this`.
 ``` cpp
 basic_istream<charT, traits>& get(basic_streambuf<char_type, traits>& sb);
@@ -2999,11 +3015,11 @@ the following occurs:
     the function calls `setstate(failbit)`).
 These conditions are tested in the order shown.[^28]
 If the function extracts no characters, it calls `setstate(failbit)`
-(which may throw `ios_base::failure` ([[iostate.flags]])).[^29]
 In any case, if `n` is greater than zero, it then stores a null
 character (using `charT()`) into the next successive location of the
 array.
@@ -3051,15 +3067,15 @@ basic_istream<charT, traits>& ignore(streamsize n = 1, int_type delim = traits::
 *Effects:* Behaves as an unformatted input function (as described
 above). After constructing a sentry object, extracts characters and
 discards them. Characters are extracted until any of the following
 occurs:
-- `n != numeric_limits<streamsize>::max()` ([[numeric.limits]]) and `n`
   characters have been extracted so far
 - end-of-file occurs on the input sequence (in which case the function
-  calls `setstate(eofbit)`, which may throw
- `ios_base::failure` ([[iostate.flags]]));
 - `traits::eq_int_type(traits::to_int_type(c), delim)` for the next
   available input character `c` (in which case `c` is extracted).
 *Remarks:* The last condition will never occur if
 `traits::eq_int_type(delim, traits::eof())`.
@@ -3089,11 +3105,11 @@ array whose first element is designated by `s`.[^30] Characters are
 extracted and stored until either of the following occurs:
 - `n` characters are stored;
 - end-of-file occurs on the input sequence (in which case the function
   calls `setstate(failbit | eofbit)`, which may throw
-  `ios_base::failure` ([[iostate.flags]])).
 *Returns:* `*this`.
 ``` cpp
 streamsize readsome(char_type* s, streamsize n);
@@ -3103,11 +3119,11 @@ streamsize readsome(char_type* s, streamsize n);
 above). After constructing a sentry object, if `!good()` calls
 `setstate(failbit)` which may throw an exception, and return. Otherwise
 extracts characters and stores them into successive locations of an
 array whose first element is designated by `s`. If
 `rdbuf()->in_avail() == -1`, calls `setstate(eofbit)` (which may throw
-`ios_base::failure` ([[iostate.flags]])), and extracts no characters;
 - If `rdbuf()->in_avail() == 0`, extracts no characters
 - If `rdbuf()->in_avail() > 0`, extracts `min(rdbuf()->in_avail(), n))`.
 *Returns:* The number of characters extracted.
@@ -3118,13 +3134,13 @@ basic_istream<charT, traits>& putback(char_type c);
 *Effects:* Behaves as an unformatted input function (as described
 above), except that the function first clears `eofbit`. After
 constructing a sentry object, if `!good()` calls `setstate(failbit)`
 which may throw an exception, and return. If `rdbuf()` is not null,
-calls `rdbuf->sputbackc()`. If `rdbuf()` is null, or if `sputbackc()`
 returns `traits::eof()`, calls `setstate(badbit)` (which may throw
-`ios_base::failure` ([[iostate.flags]])).
 [*Note 1*: This function extracts no characters, so the value returned
 by the next call to `gcount()` is 0. — *end note*]
 *Returns:* `*this`.
@@ -3135,13 +3151,13 @@ basic_istream<charT, traits>& unget();
 *Effects:* Behaves as an unformatted input function (as described
 above), except that the function first clears `eofbit`. After
 constructing a sentry object, if `!good()` calls `setstate(failbit)`
 which may throw an exception, and return. If `rdbuf()` is not null,
-calls `rdbuf()->sungetc()`. If `rdbuf()` is null, or if `sungetc()`
 returns `traits::eof()`, calls `setstate(badbit)` (which may throw
-`ios_base::failure` ([[iostate.flags]])).
 [*Note 2*: This function extracts no characters, so the value returned
 by the next call to `gcount()` is 0. — *end note*]
 *Returns:* `*this`.
@@ -3154,11 +3170,11 @@ int sync();
 above), except that it does not count the number of characters extracted
 and does not affect the value returned by subsequent calls to
 `gcount()`. After constructing a sentry object, if `rdbuf()` is a null
 pointer, returns `-1`. Otherwise, calls `rdbuf()->pubsync()` and, if
 that function returns `-1` calls `setstate(badbit)` (which may throw
-`ios_base::failure` ([[iostate.flags]]), and returns `-1`. Otherwise,
 returns zero.
 ``` cpp
 pos_type tellg();
 ```
@@ -3202,45 +3218,49 @@ function calls `setstate(failbit)` (which may throw
 *Returns:* `*this`.
 #### Standard `basic_istream` manipulators <a id="istream.manip">[[istream.manip]]</a>
 ``` cpp
 template<class charT, class traits>
   basic_istream<charT, traits>& ws(basic_istream<charT, traits>& is);
 ```
-*Effects:* Behaves as an unformatted input function
-([[istream.unformatted]]), except that it does not count the number of
-characters extracted and does not affect the value returned by
-subsequent calls to is.gcount(). After constructing a sentry object
 extracts characters as long as the next available character `c` is
 whitespace or until there are no more characters in the sequence.
 Whitespace characters are distinguished with the same criterion as used
-by `sentry::sentry` ([[istream::sentry]]). If `ws` stops extracting
 characters because there are no more available it sets `eofbit`, but not
 `failbit`.
 *Returns:* `is`.
 #### Rvalue stream extraction <a id="istream.rvalue">[[istream.rvalue]]</a>
 ``` cpp
-template <class charT, class traits, class T>
- basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>&& is, T&& x);
 ```
 *Effects:* Equivalent to:
 ``` cpp
 is >> std::forward<T>(x);
-return is;
 ```
-*Remarks:* This function shall not participate in overload resolution
-unless the expression `is >> std::forward<T>(x)` is well-formed.
 #### Class template `basic_iostream` <a id="iostreamclass">[[iostreamclass]]</a>
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
@@ -3260,62 +3280,59 @@ namespace std {
     // [iostream.dest], destructor
     virtual ~basic_iostream();
   protected:
     // [iostream.cons], constructor
-    basic_iostream(const basic_iostream& rhs) = delete;
     basic_iostream(basic_iostream&& rhs);
     // [iostream.assign], assign and swap
-    basic_iostream& operator=(const basic_iostream& rhs) = delete;
     basic_iostream& operator=(basic_iostream&& rhs);
     void swap(basic_iostream& rhs);
   };
 }
 ```
 The class template `basic_iostream` inherits a number of functions that
 allow reading input and writing output to sequences controlled by a
 stream buffer.
-##### `basic_iostream` constructors <a id="iostream.cons">[[iostream.cons]]</a>
 ``` cpp
 explicit basic_iostream(basic_streambuf<charT, traits>* sb);
 ```
-*Effects:* Constructs an object of class `basic_iostream`, initializing
-the base class subobjects with
-`basic_istream<charT, traits>(sb)` ([[istream]]) and
-`basic_ostream<charT, traits>(sb)` ([[ostream]]).
-*Postconditions:* `rdbuf() == sb` and `gcount() == 0`.
 ``` cpp
 basic_iostream(basic_iostream&& rhs);
 ```
 *Effects:* Move constructs from the rvalue `rhs` by constructing the
 `basic_istream` base class with `move(rhs)`.
-##### `basic_iostream` destructor <a id="iostream.dest">[[iostream.dest]]</a>
 ``` cpp
 virtual ~basic_iostream();
 ```
-*Effects:* Destroys an object of class `basic_iostream`.
 *Remarks:* Does not perform any operations on `rdbuf()`.
-##### `basic_iostream` assign and swap <a id="iostream.assign">[[iostream.assign]]</a>
 ``` cpp
 basic_iostream& operator=(basic_iostream&& rhs);
 ```
-*Effects:* As if by `swap(rhs)`.
 ``` cpp
 void swap(basic_iostream& rhs);
 ```
@@ -3332,22 +3349,22 @@ that inserts into stream rvalues.
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
   class basic_ostream : virtual public basic_ios<charT, traits> {
   public:
-    // types (inherited from basic_ios ([ios])):
     using char_type   = charT;
     using int_type    = typename traits::int_type;
     using pos_type    = typename traits::pos_type;
     using off_type    = typename traits::off_type;
     using traits_type = traits;
     // [ostream.cons], constructor/destructor
     explicit basic_ostream(basic_streambuf<char_type, traits>* sb);
     virtual ~basic_ostream();
-    // [ostream::sentry], prefix/suffix
     class sentry;
     // [ostream.formatted], formatted output
     basic_ostream<charT, traits>&
       operator<<(basic_ostream<charT, traits>& (*pf)(basic_ostream<charT, traits>&));
@@ -3384,15 +3401,15 @@ namespace std {
     basic_ostream<charT, traits>& seekp(pos_type);
     basic_ostream<charT, traits>& seekp(off_type, ios_base::seekdir);
   protected:
     // [ostream.cons], copy/move constructor
-    basic_ostream(const basic_ostream& rhs) = delete;
     basic_ostream(basic_ostream&& rhs);
     // [ostream.assign], assign and swap
-    basic_ostream& operator=(const basic_ostream& rhs) = delete;
     basic_ostream& operator=(basic_ostream&& rhs);
     void swap(basic_ostream& rhs);
   };
   // [ostream.inserters.character], character inserters
@@ -3406,10 +3423,28 @@ namespace std {
   template<class traits>
     basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, signed char);
   template<class traits>
     basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, unsigned char);
   template<class charT, class traits>
     basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>&, const charT*);
   template<class charT, class traits>
     basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>&, const char*);
   template<class traits>
@@ -3417,10 +3452,32 @@ namespace std {
   template<class traits>
     basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const signed char*);
   template<class traits>
     basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const unsigned char*);
 }
 ```
 The class template `basic_ostream` defines a number of member function
 signatures that assist in formatting and writing output to output
@@ -3433,26 +3490,29 @@ output functions.* Both groups of output functions generate (or
 `rdbuf()->sputc(int_type)`. They may use other public members of
 `basic_ostream` except that they shall not invoke any virtual members of
 `rdbuf()` except `overflow()`, `xsputn()`, and `sync()`.
 If one of these called functions throws an exception, then unless
-explicitly noted otherwise the output function sets `badbit` in error
-state. If `badbit` is on in `exceptions()`, the output function rethrows
-the exception without completing its actions, otherwise it does not
-throw anything and treat as an error.
-##### `basic_ostream` constructors <a id="ostream.cons">[[ostream.cons]]</a>
 ``` cpp
 explicit basic_ostream(basic_streambuf<charT, traits>* sb);
 ```
-*Effects:* Constructs an object of class `basic_ostream`, initializing
-the base class subobject with
-`basic_ios<charT, traits>::init(sb)` ([[basic.ios.cons]]).
-*Postconditions:* `rdbuf() == sb`.
 ``` cpp
 basic_ostream(basic_ostream&& rhs);
 ```
@@ -3462,31 +3522,29 @@ by default constructing the base class and calling
 ``` cpp
 virtual ~basic_ostream();
 ```
-*Effects:* Destroys an object of class `basic_ostream`.
 *Remarks:* Does not perform any operations on `rdbuf()`.
-##### Class `basic_ostream` assign and swap <a id="ostream.assign">[[ostream.assign]]</a>
 ``` cpp
 basic_ostream& operator=(basic_ostream&& rhs);
 ```
-*Effects:* As if by `swap(rhs)`.
 *Returns:* `*this`.
 ``` cpp
 void swap(basic_ostream& rhs);
 ```
 *Effects:* Calls `basic_ios<charT, traits>::swap(rhs)`.
-##### Class `basic_ostream::sentry` <a id="ostream::sentry">[[ostream::sentry]]</a>
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
   class basic_ostream<charT, traits>::sentry {
@@ -3513,11 +3571,11 @@ If `os.good()` is nonzero, prepares for formatted or unformatted output.
 If `os.tie()` is not a null pointer, calls `os.tie()->flush()`.[^31]
 If, after any preparation is completed, `os.good()` is `true`,
 `ok_ == true` otherwise, `ok_ == false`. During preparation, the
 constructor may call `setstate(failbit)` (which may throw
-`ios_base::failure` ([[iostate.flags]]))[^32]
 ``` cpp
 ~sentry();
 ```
@@ -3530,11 +3588,11 @@ sets `badbit` in `os.rdstate()` without propagating an exception.
 explicit operator bool() const;
 ```
 *Effects:* Returns `ok_`.
-##### `basic_ostream` seek members <a id="ostream.seeks">[[ostream.seeks]]</a>
 Each seek member function begins execution by constructing an object of
 class `sentry`. It returns by destroying the `sentry` object.
 ``` cpp
@@ -3573,12 +3631,12 @@ function calls `setstate(failbit)` (which may throw
 Each formatted output function begins execution by constructing an
 object of class `sentry`. If this object returns `true` when converted
 to a value of type `bool`, the function endeavors to generate the
 requested output. If the generation fails, then the formatted output
 function does `setstate(ios_base::failbit)`, which might throw an
-exception. If an exception is thrown during output, then `ios::badbit`
-is turned on[^33] in `*this`’s error state. If
 `(exceptions()&badbit) != 0` then the exception is rethrown. Whether or
 not an exception is thrown, the `sentry` object is destroyed before
 leaving the formatted output function. If no exception is thrown, the
 result of the formatted output function is `*this`.
@@ -3719,13 +3777,13 @@ in  [[ostream.formatted.reqmts]]).
 ``` cpp
 basic_ostream<charT, traits>& operator<<(basic_streambuf<charT, traits>* sb);
 ```
-*Effects:* Behaves as an unformatted output function
-([[ostream.unformatted]]). After the sentry object is constructed, if
-`sb` is null calls `setstate(badbit)` (which may throw
 `ios_base::failure`).
 Gets characters from `sb` and inserts them in `*this`. Characters are
 read from `sb` and inserted until any of the following occurs:
@@ -3733,14 +3791,14 @@ read from `sb` and inserted until any of the following occurs:
 - inserting in the output sequence fails (in which case the character to
   be inserted is not extracted);
 - an exception occurs while getting a character from `sb`.
 If the function inserts no characters, it calls `setstate(failbit)`
-(which may throw `ios_base::failure` ([[iostate.flags]])). If an
-exception was thrown while extracting a character, the function sets
-`failbit` in error state, and if `failbit` is on in `exceptions()` the
-caught exception is rethrown.
 *Returns:* `*this`.
 ``` cpp
 basic_ostream<charT, traits>& operator<<(nullptr_t);
@@ -3750,11 +3808,11 @@ basic_ostream<charT, traits>& operator<<(nullptr_t);
 ``` cpp
 return *this << s;
 ```
-where `s` is an *implementation-defined* NTCTS ([[defns.ntcts]]).
 ##### Character inserter function templates <a id="ostream.inserters.character">[[ostream.inserters.character]]</a>
 ``` cpp
 template<class charT, class traits>
@@ -3770,16 +3828,16 @@ template<class traits>
 template<class traits>
   basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out, unsigned char c);
 ```
 *Effects:* Behaves as a formatted output
-function ([[ostream.formatted.reqmts]]) of `out`. Constructs a
-character sequence `seq`. If `c` has type `char` and the character type
-of the stream is not `char`, then `seq` consists of `out.widen(c)`;
-otherwise `seq` consists of `c`. Determines padding for `seq` as
-described in  [[ostream.formatted.reqmts]]. Inserts `seq` into `out`.
-Calls `os.width(0)`.
 *Returns:* `out`.
 ``` cpp
 template<class charT, class traits>
@@ -3793,17 +3851,17 @@ template<class traits>
 template<class traits>
   basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out,
                                           const unsigned char* s);
 ```
-*Requires:* `s` shall not be a null pointer.
 *Effects:* Behaves like a formatted inserter (as described
 in  [[ostream.formatted.reqmts]]) of `out`. Creates a character sequence
 `seq` of `n` characters starting at `s`, each widened using
-`out.widen()` ([[basic.ios.members]]), where `n` is the number that
-would be computed as if by:
 - `traits::length(s)` for the overload where the first argument is of
   type `basic_ostream<charT, traits>&` and the second is of type
   `const charT*`, and also for the overload where the first argument is
   of type `basic_ostream<char, traits>&` and the second is of type
@@ -3824,11 +3882,11 @@ in  [[ostream.formatted.reqmts]]. Inserts `seq` into `out`. Calls
 Each unformatted output function begins execution by constructing an
 object of class `sentry`. If this object returns `true`, while
 converting to a value of type `bool`, the function endeavors to generate
 the requested output. If an exception is thrown during output, then
-`ios::badbit` is turned on[^36] in `*this`’s error state. If
 `(exceptions() & badbit) != 0` then the exception is rethrown. In any
 case, the unformatted output function ends by destroying the sentry
 object, then, if no exception was thrown, returning the value specified
 for the unformatted output function.
@@ -3838,12 +3896,12 @@ basic_ostream<charT, traits>& put(char_type c);
 *Effects:* Behaves as an unformatted output function (as described
 above). After constructing a sentry object, inserts the character `c`,
 if possible.[^37]
-Otherwise, calls `setstate(badbit)` (which may throw
-`ios_base::failure` ([[iostate.flags]])).
 *Returns:* `*this`.
 ``` cpp
 basic_ostream& write(const char_type* s, streamsize n);
@@ -3855,12 +3913,12 @@ from successive locations of an array whose first element is designated
 by `s`.[^38] Characters are inserted until either of the following
 occurs:
 - `n` characters are inserted;
 - inserting in the output sequence fails (in which case the function
-  calls `setstate(badbit)`, which may throw
- `ios_base::failure` ([[iostate.flags]])).
 *Returns:* `*this`.
 ``` cpp
 basic_ostream& flush();
@@ -3868,17 +3926,20 @@ basic_ostream& flush();
 *Effects:* Behaves as an unformatted output function (as described
 above). If `rdbuf()` is not a null pointer, constructs a sentry object.
 If this object returns `true` when converted to a value of type `bool`
 the function calls `rdbuf()->pubsync()`. If that function returns -1
-calls `setstate(badbit)` (which may throw
-`ios_base::failure` ([[iostate.flags]])). Otherwise, if the sentry
-object returns `false`, does nothing.
 *Returns:* `*this`.
-#### Standard `basic_ostream` manipulators <a id="ostream.manip">[[ostream.manip]]</a>
 ``` cpp
 template<class charT, class traits>
   basic_ostream<charT, traits>& endl(basic_ostream<charT, traits>& os);
 ```
@@ -3904,23 +3965,64 @@ template <class charT, class traits>
 *Effects:* Calls `os.flush()`.
 *Returns:* `os`.
 #### Rvalue stream insertion <a id="ostream.rvalue">[[ostream.rvalue]]</a>
 ``` cpp
-template <class charT, class traits, class T>
- basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>&& os, const T& x);
 ```
 *Effects:* As if by: `os << x;`
-*Returns:* `os`.
-*Remarks:* This function shall not participate in overload resolution
-unless the expression `os << x` is well-formed.
 ### Standard manipulators <a id="std.manip">[[std.manip]]</a>
 The header `<iomanip>` defines several functions that support extractors
 and inserters that alter information maintained by class `ios_base` and
@@ -3942,14 +4044,14 @@ void f(ios_base& str, ios_base::fmtflags mask) {
   // reset specified flags
   str.setf(ios_base::fmtflags(0), mask);
 }
 ```
-The expression `out << resetiosflags(mask)` shall have type
 `basic_ostream<charT, traits>&` and value `out`. The expression
-`in >> resetiosflags(mask)` shall have type
-`basic_istream<charT, traits>&` and value `in`.
 ``` cpp
 unspecified setiosflags(ios_base::fmtflags mask);
 ```
@@ -3965,14 +4067,14 @@ void f(ios_base& str, ios_base::fmtflags mask) {
   // set specified flags
   str.setf(mask);
 }
 ```
-The expression `out << setiosflags(mask)` shall have type
 `basic_ostream<charT, traits>&` and value `out`. The expression
-`in >> setiosflags(mask)` shall have type `basic_istream<charT,`
-`traits>&` and value `in`.
 ``` cpp
 unspecified setbase(int base);
 ```
@@ -3991,14 +4093,14 @@ void f(ios_base& str, int base) {
       base == 16 ? ios_base::hex :
       ios_base::fmtflags(0), ios_base::basefield);
 }
 ```
-The expression `out << setbase(base)` shall have type
 `basic_ostream<charT, traits>&` and value `out`. The expression
-`in >> setbase(base)` shall have type `basic_istream<charT, traits>&`
-and value `in`.
 ``` cpp
 unspecified setfill(char_type c);
 ```
@@ -4013,11 +4115,11 @@ void f(basic_ios<charT, traits>& str, charT c) {
   // set fill character
   str.fill(c);
 }
 ```
-The expression `out << setfill(c)` shall have type
 `basic_ostream<charT, traits>&` and value `out`.
 ``` cpp
 unspecified setprecision(int n);
 ```
@@ -4034,14 +4136,14 @@ void f(ios_base& str, int n) {
   // set precision
   str.precision(n);
 }
 ```
-The expression `out << setprecision(n)` shall have type
 `basic_ostream<charT, traits>&` and value `out`. The expression
-`in >> setprecision(n)` shall have type `basic_istream<charT, traits>&`
-and value `in`.
 ``` cpp
 unspecified setw(int n);
 ```
@@ -4057,14 +4159,13 @@ void f(ios_base& str, int n) {
   // set width
   str.width(n);
 }
 ```
-The expression `out << setw(n)` shall have type
-`basic_ostream<charT, traits>&` and value `out`. The expression
-`in >> setw(n)` shall have type `basic_istream<charT, traits>&` and
-value `in`.
 ### Extended manipulators <a id="ext.manip">[[ext.manip]]</a>
 The header `<iomanip>` defines several functions that support extractors
 and inserters that allow for the parsing and formatting of sequences and
@@ -4072,15 +4173,15 @@ values for money and time.
 ``` cpp
 template<class moneyT> unspecified get_money(moneyT& mon, bool intl = false);
 ```
-*Requires:* The type `moneyT` shall be either `long double` or a
-specialization of the `basic_string` template (Clause  [[strings]]).
 *Effects:* The expression `in >> get_money(mon, intl)` described below
-behaves as a formatted input function ([[istream.formatted.reqmts]]).
 *Returns:* An object of unspecified type such that if `in` is an object
 of type `basic_istream<charT, traits>` then the expression
 `in >> get_money(mon, intl)` behaves as if it called `f(in, mon, intl)`,
 where the function `f` is defined as:
@@ -4099,24 +4200,24 @@ void f(basic_ios<charT, traits>& str, moneyT& mon, bool intl) {
   if (ios_base::goodbit != err)
     str.setstate(err);
 }
 ```
-The expression `in >> get_money(mon, intl)` shall have type
 `basic_istream<charT, traits>&` and value `in`.
 ``` cpp
 template<class moneyT> unspecified put_money(const moneyT& mon, bool intl = false);
 ```
-*Requires:* The type `moneyT` shall be either `long double` or a
-specialization of the `basic_string` template (Clause  [[strings]]).
 *Returns:* An object of unspecified type such that if `out` is an object
 of type `basic_ostream<charT, traits>` then the expression
 `out << put_money(mon, intl)` behaves as a formatted output
-function ([[ostream.formatted.reqmts]]) that calls `f(out, mon, intl)`,
 where the function `f` is defined as:
 ``` cpp
 template<class charT, class traits, class moneyT>
 void f(basic_ios<charT, traits>& str, const moneyT& mon, bool intl) {
@@ -4125,25 +4226,24 @@ void f(basic_ios<charT, traits>& str, const moneyT& mon, bool intl) {
   const MoneyPut& mp = use_facet<MoneyPut>(str.getloc());
   const Iter end = mp.put(Iter(str.rdbuf()), intl, str, str.fill(), mon);
   if (end.failed())
-    str.setstate(ios::badbit);
 }
 ```
-The expression `out << put_money(mon, intl)` shall have type
 `basic_ostream<charT, traits>&` and value `out`.
 ``` cpp
 template<class charT> unspecified get_time(struct tm* tmb, const charT* fmt);
 ```
-*Requires:* The argument `tmb` shall be a valid pointer to an object of
-type `struct tm`. The argument `fmt` shall be a valid pointer to an
-array of objects of type `charT` with `char_traits<charT>::length(fmt)`
-elements.
 *Returns:* An object of unspecified type such that if `in` is an object
 of type `basic_istream<charT, traits>` then the expression
 `in >> get_time(tmb, fmt)` behaves as if it called `f(in, tmb, fmt)`,
 where the function `f` is defined as:
@@ -4163,21 +4263,20 @@ void f(basic_ios<charT, traits>& str, struct tm* tmb, const charT* fmt) {
   if (err != ios_base::goodbit)
     str.setstate(err);
 }
 ```
-The expression `in >> get_time(tmb, fmt)` shall have type
 `basic_istream<charT, traits>&` and value `in`.
 ``` cpp
 template<class charT> unspecified put_time(const struct tm* tmb, const charT* fmt);
 ```
-*Requires:* The argument `tmb` shall be a valid pointer to an object of
-type `struct tm`, and the argument `fmt` shall be a valid pointer to an
-array of objects of type `charT` with `char_traits<charT>::length(fmt)`
-elements.
 *Returns:* An object of unspecified type such that if `out` is an object
 of type `basic_ostream<charT, traits>` then the expression
 `out << put_time(tmb, fmt)` behaves as if it called `f(out, tmb, fmt)`,
 where the function `f` is defined as:
@@ -4195,11 +4294,11 @@ void f(basic_ios<charT, traits>& str, const struct tm* tmb, const charT* fmt) {
   if (end.failed())
     str.setstate(ios_base::badbit);
 }
 ```
-The expression `out << put_time(tmb, fmt)` shall have type
 `basic_ostream<charT, traits>&` and value `out`.
 ### Quoted manipulators <a id="quoted.manip">[[quoted.manip]]</a>
 [*Note 1*: Quoted manipulators provide string insertion and extraction
@@ -4222,13 +4321,12 @@ template <class charT, class traits>
 *Returns:* An object of unspecified type such that if `out` is an
 instance of `basic_ostream` with member type `char_type` the same as
 `charT` and with member type `traits_type`, which in the second and
 third forms is the same as `traits`, then the expression
 `out << quoted(s, delim, escape)` behaves as a formatted output
-function ([[ostream.formatted.reqmts]]) of `out`. This forms a
-character sequence `seq`, initially consisting of the following
-elements:
 - `delim`.
 - Each character in `s`. If the character to be output is equal to
   `escape` or `delim`, as determined by `traits_type::eq`, first output
   `escape`.
@@ -4236,11 +4334,11 @@ elements:
 Let `x` be the number of elements initially in `seq`. Then padding is
 determined for `seq` as described in  [[ostream.formatted.reqmts]],
 `seq` is inserted as if by calling `out.rdbuf()->sputn(seq, n)`, where
 `n` is the larger of `out.width()` and `x`, and `out.width(0)` is
-called. The expression `out << quoted(s, delim, escape)` shall have type
 `basic_ostream<charT, traits>&` and value `out`.
 ``` cpp
 template<class charT, class traits, class Allocator>
   unspecified quoted(basic_string<charT, traits, Allocator>& s,
@@ -4251,12 +4349,13 @@ template <class charT, class traits, class Allocator>
 - If `in` is an instance of `basic_istream` with member types
   `char_type` and `traits_type` the same as `charT` and `traits`,
   respectively, then the expression `in >> quoted(s, delim, escape)`
   behaves as if it extracts the following characters from `in` using
-  `operator>>(basic_istream<charT, traits>&, charT&)` ([[istream.extractors]])
-  which may throw `ios_base::failure` ([[ios::failure]]):
   - If the first character extracted is equal to `delim`, as determined
     by `traits_type::eq`, then:
     - Turn off the `skipws` flag.
     - `s.clear()`
     - Until an unescaped `delim` character is reached or `!in`, extract
@@ -4270,14 +4369,13 @@ template <class charT, class traits, class Allocator>
   `char_type` and `traits_type` the same as `charT` and `traits`,
   respectively, then the expression `out << quoted(s, delim, escape)`
   behaves as specified for the
   `const basic_string<charT, traits, Allocator>&` overload of the
   `quoted` function.
-The expression `in >> quoted(s, delim, escape)` shall have type
-`basic_istream<charT, traits>&` and value `in`. The expression
-`out << quoted(s, delim, escape)` shall have type
   `basic_ostream<charT, traits>&` and value `out`.
 ## String-based streams <a id="string.streams">[[string.streams]]</a>
 ### Header `<sstream>` synopsis <a id="sstream.syn">[[sstream.syn]]</a>
@@ -4330,26 +4428,55 @@ namespace std {
     using off_type       = typename traits::off_type;
     using traits_type    = traits;
     using allocator_type = Allocator;
     // [stringbuf.cons], constructors
     explicit basic_stringbuf(
       ios_base::openmode which = ios_base::in | ios_base::out);
     explicit basic_stringbuf(
- const basic_string<charT, traits, Allocator>& str,
       ios_base::openmode which = ios_base::in | ios_base::out);
- basic_stringbuf(const basic_stringbuf& rhs) = delete;
     basic_stringbuf(basic_stringbuf&& rhs);
     // [stringbuf.assign], assign and swap
-    basic_stringbuf& operator=(const basic_stringbuf& rhs) = delete;
     basic_stringbuf& operator=(basic_stringbuf&& rhs);
-    void swap(basic_stringbuf& rhs);
-    // [stringbuf.members], get and set
-    basic_string<charT, traits, Allocator> str() const;
     void str(const basic_string<charT, traits, Allocator>& s);
   protected:
     // [stringbuf.virtuals], overridden virtual functions
     int_type underflow() override;
     int_type pbackfail(int_type c = traits::eof()) override;
@@ -4363,66 +4490,120 @@ namespace std {
                      ios_base::openmode which
                       = ios_base::in | ios_base::out) override;
   private:
     ios_base::openmode mode;                        // exposition only
   };
   template<class charT, class traits, class Allocator>
     void swap(basic_stringbuf<charT, traits, Allocator>& x,
-              basic_stringbuf<charT, traits, Allocator>& y);
 }
 ```
 The class `basic_stringbuf` is derived from `basic_streambuf` to
 associate possibly the input sequence and possibly the output sequence
 with a sequence of arbitrary *characters*. The sequence can be
 initialized from, or made available as, an object of class
 `basic_string`.
-For the sake of exposition, the maintained data is presented here as:
 - `ios_base::openmode mode`, has `in` set if the input sequence can be
   read, and `out` set if the output sequence can be written.
-#### `basic_stringbuf` constructors <a id="stringbuf.cons">[[stringbuf.cons]]</a>
 ``` cpp
-explicit basic_stringbuf(
-  ios_base::openmode which = ios_base::in | ios_base::out);
 ```
-*Effects:* Constructs an object of class `basic_stringbuf`, initializing
-the base class with `basic_streambuf()` ([[streambuf.cons]]), and
-initializing `mode` with `which`.
-*Postconditions:* `str() == ""`.
 ``` cpp
 explicit basic_stringbuf(
   const basic_string<charT, traits, Allocator>& s,
   ios_base::openmode which = ios_base::in | ios_base::out);
 ```
-*Effects:* Constructs an object of class `basic_stringbuf`, initializing
-the base class with `basic_streambuf()` ([[streambuf.cons]]), and
-initializing `mode` with `which`. Then calls `str(s)`.
 ``` cpp
 basic_stringbuf(basic_stringbuf&& rhs);
 ```
-*Effects:* Move constructs from the rvalue `rhs`. It is
-*implementation-defined* whether the sequence pointers in `*this`
-(`eback()`, `gptr()`, `egptr()`, `pbase()`, `pptr()`, `epptr()`) obtain
-the values which `rhs` had. Whether they do or not, `*this` and `rhs`
-reference separate buffers (if any at all) after the construction. The
-openmode, locale and any other state of `rhs` is also copied.
-*Postconditions:* Let `rhs_p` refer to the state of `rhs` just prior to
-this construction and let `rhs_a` refer to the state of `rhs` just after
-this construction.
 - `str() == rhs_p.str()`
 - `gptr() - eback() == rhs_p.gptr() - rhs_p.eback()`
 - `egptr() - eback() == rhs_p.egptr() - rhs_p.eback()`
 - `pptr() - pbase() == rhs_p.pptr() - rhs_p.pbase()`
@@ -4431,12 +4612,14 @@ this construction.
 - `if (gptr()) gptr() != rhs_a.gptr()`
 - `if (egptr()) egptr() != rhs_a.egptr()`
 - `if (pbase()) pbase() != rhs_a.pbase()`
 - `if (pptr()) pptr() != rhs_a.pptr()`
 - `if (epptr()) epptr() != rhs_a.epptr()`
-#### Assign and swap <a id="stringbuf.assign">[[stringbuf.assign]]</a>
 ``` cpp
 basic_stringbuf& operator=(basic_stringbuf&& rhs);
 ```
@@ -4445,62 +4628,165 @@ would have had if it had been move constructed from `rhs`
 (see  [[stringbuf.cons]]).
 *Returns:* `*this`.
 ``` cpp
-void swap(basic_stringbuf& rhs);
 ```
 *Effects:* Exchanges the state of `*this` and `rhs`.
 ``` cpp
 template<class charT, class traits, class Allocator>
   void swap(basic_stringbuf<charT, traits, Allocator>& x,
-            basic_stringbuf<charT, traits, Allocator>& y);
 ```
-*Effects:* As if by `x.swap(y)`.
 #### Member functions <a id="stringbuf.members">[[stringbuf.members]]</a>
 ``` cpp
-basic_string<charT, traits, Allocator> str() const;
-```
-*Returns:* A `basic_string` object whose content is equal to the
-`basic_stringbuf` underlying character sequence. If the
-`basic_stringbuf` was created only in input mode, the resultant
-`basic_string` contains the character sequence in the range \[`eback()`,
-`egptr()`). If the `basic_stringbuf` was created with
-`which & ios_base::out` being nonzero then the resultant `basic_string`
-contains the character sequence in the range \[`pbase()`, `high_mark`),
-where `high_mark` represents the position one past the highest
-initialized character in the buffer. Characters can be initialized by
-writing to the stream, by constructing the `basic_stringbuf` with a
-`basic_string`, or by calling the `str(basic_string)` member function.
-In the case of calling the `str(basic_string)` member function, all
-characters initialized prior to the call are now considered
-uninitialized (except for those characters re-initialized by the new
-`basic_string`). Otherwise the `basic_stringbuf` has been created in
-neither input nor output mode and a zero length `basic_string` is
-returned.
 ``` cpp
 void str(const basic_string<charT, traits, Allocator>& s);
 ```
-*Effects:* Copies the content of `s` into the `basic_stringbuf`
-underlying character sequence and initializes the input and output
-sequences according to `mode`.
-*Postconditions:* If `mode & ios_base::out` is nonzero, `pbase()` points
-to the first underlying character and `epptr()` `>= pbase() + s.size()`
-holds; in addition, if `mode & ios_base::ate` is nonzero,
-`pptr() == pbase() + s.size()` holds, otherwise `pptr() == pbase()` is
-`true`. If `mode & ios_base::in` is nonzero, `eback()` points to the
-first underlying character, and both `gptr() == eback()` and
-`egptr() == eback() + s.size()` hold.
 #### Overridden virtual functions <a id="stringbuf.virtuals">[[stringbuf.virtuals]]</a>
 ``` cpp
 int_type underflow() override;
@@ -4527,11 +4813,11 @@ sequence, if possible, in one of three ways:
   `ios_base::out` is nonzero, assigns `c` to `*``gptr()`. Returns: `c`.
 - If `traits::eq_int_type(c, traits::eof())` returns `true` and if the
   input sequence has a putback position available, assigns `gptr() - 1`
   to `gptr()`. Returns: `traits::not_eof(c)`.
-*Returns:* `traits::eof()` to indicate failure.
 *Remarks:* If the function can succeed in more than one of these ways,
 it is unspecified which way is chosen.
 ``` cpp
@@ -4550,56 +4836,55 @@ sequence, if possible, in one of two ways:
   `traits::eof()`.
 *Remarks:* The function can alter the number of write positions
 available as a result of any call.
-*Returns:* `traits::eof()` to indicate failure.
-The function can make a write position available only if
-`(mode & ios_base::out) != 0`. To make a write position available, the
-function reallocates (or initially allocates) an array object with a
-sufficient number of elements to hold the current array object (if any),
-plus at least one additional write position. If
-`(mode & ios_base::in) != 0`, the function alters the read end pointer
-`egptr()` to point just past the new write position.
 ``` cpp
 pos_type seekoff(off_type off, ios_base::seekdir way,
                  ios_base::openmode which
                    = ios_base::in | ios_base::out) override;
 ```
 *Effects:* Alters the stream position within one of the controlled
-sequences, if possible, as indicated in
-Table  [[tab:iostreams.seekoff.positioning]].
-**Table: `seekoff` positioning** <a id="tab:iostreams.seekoff.positioning">[tab:iostreams.seekoff.positioning]</a>
 | Conditions                                                                                                                     | Result                                            |
-| ------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------- |
-| `(which & ios_base::in)`` == ios_base::in` | positions the input sequence                      |
-| `(which & ios_base::out)`` == ios_base::out` | positions the output sequence                     |
-| `(which & (ios_base::in |`<br> `ios_base::out)) ==`<br> `(ios_base::in) |`<br> `ios_base::out))`<br> and `way ==` either<br> `ios_base::beg` or<br> `ios_base::end` | positions both the input and the output sequences |
 | Otherwise                                                                                                                      | the positioning operation fails.                  |
-For a sequence to be positioned, if its next pointer (either `gptr()` or
-`pptr()`) is a null pointer and the new offset `newoff` is nonzero, the
-positioning operation fails. Otherwise, the function determines `newoff`
-as indicated in Table  [[tab:iostreams.newoff.values]].
-**Table: `newoff` values** <a id="tab:iostreams.newoff.values">[tab:iostreams.newoff.values]</a>
 | Condition              | `newoff` Value                                                          |
 | ---------------------- | ----------------------------------------------------------------------- |
 | `way == ios_base::beg` | 0                                                                       |
 | `way == ios_base::cur` | the next pointer minus the beginning pointer (`xnext - xbeg`).          |
 | `way == ios_base::end` | the high mark pointer minus the beginning pointer (`high_mark - xbeg`). |
 If `(newoff + off) < 0`, or if `newoff + off` refers to an uninitialized
-character ([[stringbuf.members]]), the positioning operation fails.
 Otherwise, the function assigns `xbeg + newoff + off` to the next
 pointer `xnext`.
 *Returns:* `pos_type(newoff)`, constructed from the resultant offset
 `newoff` (of type `off_type`), that stores the resultant stream
@@ -4641,28 +4926,52 @@ namespace std {
     using off_type       = typename traits::off_type;
     using traits_type    = traits;
     using allocator_type = Allocator;
     // [istringstream.cons], constructors
     explicit basic_istringstream(
       ios_base::openmode which = ios_base::in);
     explicit basic_istringstream(
- const basic_string<charT, traits, Allocator>& str,
       ios_base::openmode which = ios_base::in);
- basic_istringstream(const basic_istringstream& rhs) = delete;
     basic_istringstream(basic_istringstream&& rhs);
     // [istringstream.assign], assign and swap
-    basic_istringstream& operator=(const basic_istringstream& rhs) = delete;
     basic_istringstream& operator=(basic_istringstream&& rhs);
     void swap(basic_istringstream& rhs);
     // [istringstream.members], members
     basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
-    basic_string<charT, traits, Allocator> str() const;
     void str(const basic_string<charT, traits, Allocator>& s);
   private:
     basic_stringbuf<charT, traits, Allocator> sb;   // exposition only
   };
   template<class charT, class traits, class Allocator>
@@ -4677,87 +4986,157 @@ uses a `basic_stringbuf<charT, traits, Allocator>` object to control the
 associated storage. For the sake of exposition, the maintained data is
 presented here as:
 - `sb`, the `stringbuf` object.
-#### `basic_istringstream` constructors <a id="istringstream.cons">[[istringstream.cons]]</a>
 ``` cpp
-explicit basic_istringstream(ios_base::openmode which = ios_base::in);
 ```
-*Effects:* Constructs an object of class
-`basic_istringstream<charT, traits>`, initializing the base class with
-`basic_istream(&sb)` and initializing `sb` with
-`basic_stringbuf<charT, traits, Allocator>(which | ios_base::in))` ([[stringbuf.cons]]).
 ``` cpp
 explicit basic_istringstream(
-  const basic_string<charT, traits, Allocator>& str,
   ios_base::openmode which = ios_base::in);
 ```
-*Effects:* Constructs an object of class
-`basic_istringstream<charT, traits>`, initializing the base class with
-`basic_istream(&sb)` and initializing `sb` with
-`basic_stringbuf<charT, traits, Allocator>(str, which | ios_base::in))` ([[stringbuf.cons]]).
 ``` cpp
 basic_istringstream(basic_istringstream&& rhs);
 ```
 *Effects:* Move constructs from the rvalue `rhs`. This is accomplished
 by move constructing the base class, and the contained
-`basic_stringbuf`. Next `basic_istream<charT, traits>::set_rdbuf(&sb)`
-is called to install the contained `basic_stringbuf`.
-#### Assign and swap <a id="istringstream.assign">[[istringstream.assign]]</a>
-``` cpp
-basic_istringstream& operator=(basic_istringstream&& rhs);
-```
-*Effects:* Move assigns the base and members of `*this` from the base
-and corresponding members of `rhs`.
-*Returns:* `*this`.
 ``` cpp
 void swap(basic_istringstream& rhs);
 ```
-*Effects:* Exchanges the state of `*this` and `rhs` by calling
-`basic_istream<charT, traits>::swap(rhs)` and `sb.swap(rhs.sb)`.
 ``` cpp
 template<class charT, class traits, class Allocator>
   void swap(basic_istringstream<charT, traits, Allocator>& x,
             basic_istringstream<charT, traits, Allocator>& y);
 ```
-*Effects:* As if by `x.swap(y)`.
 #### Member functions <a id="istringstream.members">[[istringstream.members]]</a>
 ``` cpp
 basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
 ```
 *Returns:*
-`const_cast<basic_stringbuf<charT, traits, Allocator>*>(&sb)`.
 ``` cpp
-basic_string<charT, traits, Allocator> str() const;
 ```
-*Returns:* `rdbuf()->str()`.
 ``` cpp
 void str(const basic_string<charT, traits, Allocator>& s);
 ```
-*Effects:* Calls `rdbuf()->str(s)`.
 ### Class template `basic_ostringstream` <a id="ostringstream">[[ostringstream]]</a>
 ``` cpp
 namespace std {
@@ -4771,28 +5150,53 @@ namespace std {
     using off_type       = typename traits::off_type;
     using traits_type    = traits;
     using allocator_type = Allocator;
     // [ostringstream.cons], constructors
     explicit basic_ostringstream(
       ios_base::openmode which = ios_base::out);
     explicit basic_ostringstream(
- const basic_string<charT, traits, Allocator>& str,
       ios_base::openmode which = ios_base::out);
- basic_ostringstream(const basic_ostringstream& rhs) = delete;
     basic_ostringstream(basic_ostringstream&& rhs);
     // [ostringstream.assign], assign and swap
-    basic_ostringstream& operator=(const basic_ostringstream& rhs) = delete;
     basic_ostringstream& operator=(basic_ostringstream&& rhs);
     void swap(basic_ostringstream& rhs);
     // [ostringstream.members], members
     basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
-    basic_string<charT, traits, Allocator> str() const;
     void str(const basic_string<charT, traits, Allocator>& s);
    private:
     basic_stringbuf<charT, traits, Allocator> sb;   // exposition only
   };
   template<class charT, class traits, class Allocator>
@@ -4806,88 +5210,157 @@ writing objects of class `basic_string<{}charT, traits, Allocator>`. It
 uses a `basic_stringbuf` object to control the associated storage. For
 the sake of exposition, the maintained data is presented here as:
 - `sb`, the `stringbuf` object.
-#### `basic_ostringstream` constructors <a id="ostringstream.cons">[[ostringstream.cons]]</a>
 ``` cpp
 explicit basic_ostringstream(
   ios_base::openmode which = ios_base::out);
 ```
-*Effects:* Constructs an object of class `basic_ostringstream`,
-initializing the base class with `basic_ostream(&sb)` and initializing
-`sb` with
-`basic_stringbuf<charT, traits, Allocator>(which | ios_base::out))` ([[stringbuf.cons]]).
 ``` cpp
 explicit basic_ostringstream(
- const basic_string<charT, traits, Allocator>& str,
   ios_base::openmode which = ios_base::out);
 ```
-*Effects:* Constructs an object of class
-`basic_ostringstream<charT, traits>`, initializing the base class with
-`basic_ostream(&sb)` and initializing `sb` with
-`basic_stringbuf<charT, traits, Allocator>(str, which | ios_base::out))` ([[stringbuf.cons]]).
 ``` cpp
 basic_ostringstream(basic_ostringstream&& rhs);
 ```
 *Effects:* Move constructs from the rvalue `rhs`. This is accomplished
 by move constructing the base class, and the contained
-`basic_stringbuf`. Next `basic_ostream<charT, traits>::set_rdbuf(&sb)`
-is called to install the contained `basic_stringbuf`.
-#### Assign and swap <a id="ostringstream.assign">[[ostringstream.assign]]</a>
-``` cpp
-basic_ostringstream& operator=(basic_ostringstream&& rhs);
-```
-*Effects:* Move assigns the base and members of `*this` from the base
-and corresponding members of `rhs`.
-*Returns:* `*this`.
 ``` cpp
 void swap(basic_ostringstream& rhs);
 ```
-*Effects:* Exchanges the state of `*this` and `rhs` by calling
-`basic_ostream<charT, traits>::swap(rhs)` and `sb.swap(rhs.sb)`.
 ``` cpp
 template<class charT, class traits, class Allocator>
   void swap(basic_ostringstream<charT, traits, Allocator>& x,
             basic_ostringstream<charT, traits, Allocator>& y);
 ```
-*Effects:* As if by `x.swap(y)`.
 #### Member functions <a id="ostringstream.members">[[ostringstream.members]]</a>
 ``` cpp
 basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
 ```
 *Returns:*
-`const_cast<basic_stringbuf<charT, traits, Allocator>*>(&sb)`.
 ``` cpp
-basic_string<charT, traits, Allocator> str() const;
 ```
-*Returns:* `rdbuf()->str()`.
 ``` cpp
 void str(const basic_string<charT, traits, Allocator>& s);
 ```
-*Effects:* Calls `rdbuf()->str(s)`.
 ### Class template `basic_stringstream` <a id="stringstream">[[stringstream]]</a>
 ``` cpp
 namespace std {
@@ -4901,27 +5374,52 @@ namespace std {
     using off_type       = typename traits::off_type;
     using traits_type    = traits;
     using allocator_type = Allocator;
     // [stringstream.cons], constructors
     explicit basic_stringstream(
       ios_base::openmode which = ios_base::out | ios_base::in);
     explicit basic_stringstream(
- const basic_string<charT, traits, Allocator>& str,
       ios_base::openmode which = ios_base::out | ios_base::in);
- basic_stringstream(const basic_stringstream& rhs) = delete;
     basic_stringstream(basic_stringstream&& rhs);
     // [stringstream.assign], assign and swap
-    basic_stringstream& operator=(const basic_stringstream& rhs) = delete;
     basic_stringstream& operator=(basic_stringstream&& rhs);
     void swap(basic_stringstream& rhs);
     // [stringstream.members], members
     basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
-    basic_string<charT, traits, Allocator> str() const;
- void str(const basic_string<charT, traits, Allocator>& str);
   private:
     basic_stringbuf<charT, traits> sb;  // exposition only
   };
@@ -4938,87 +5436,160 @@ and writing from objects of class
 associated sequence. For the sake of exposition, the maintained data is
 presented here as
 - `sb`, the `stringbuf` object.
-#### `basic_stringstream` constructors <a id="stringstream.cons">[[stringstream.cons]]</a>
 ``` cpp
 explicit basic_stringstream(
   ios_base::openmode which = ios_base::out | ios_base::in);
 ```
-*Effects:* Constructs an object of class
-`basic_stringstream<charT, traits>`, initializing the base class with
-`basic_iostream(&sb)` and initializing `sb` with
-`basic_stringbuf<charT, traits, Allocator>(which)`.
 ``` cpp
 explicit basic_stringstream(
- const basic_string<charT, traits, Allocator>& str,
   ios_base::openmode which = ios_base::out | ios_base::in);
 ```
-*Effects:* Constructs an object of class
-`basic_stringstream<charT, traits>`, initializing the base class with
-`basic_iostream(&sb)` and initializing `sb` with
-`basic_stringbuf<charT, traits, Allocator>(str, which)`.
 ``` cpp
 basic_stringstream(basic_stringstream&& rhs);
 ```
 *Effects:* Move constructs from the rvalue `rhs`. This is accomplished
 by move constructing the base class, and the contained
-`basic_stringbuf`. Next `basic_istream<charT, traits>::set_rdbuf(&sb)`
-is called to install the contained `basic_stringbuf`.
-#### Assign and swap <a id="stringstream.assign">[[stringstream.assign]]</a>
-``` cpp
-basic_stringstream& operator=(basic_stringstream&& rhs);
-```
-*Effects:* Move assigns the base and members of `*this` from the base
-and corresponding members of `rhs`.
-*Returns:* `*this`.
 ``` cpp
 void swap(basic_stringstream& rhs);
 ```
-*Effects:* Exchanges the state of `*this` and `rhs` by calling
-`basic_iostream<charT,traits>::swap(rhs)` and `sb.swap(rhs.sb)`.
 ``` cpp
 template<class charT, class traits, class Allocator>
   void swap(basic_stringstream<charT, traits, Allocator>& x,
             basic_stringstream<charT, traits, Allocator>& y);
 ```
-*Effects:* As if by `x.swap(y)`.
 #### Member functions <a id="stringstream.members">[[stringstream.members]]</a>
 ``` cpp
 basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
 ```
-*Returns:* `const_cast<basic_stringbuf<charT, traits, Allocator>*>(&sb)`
 ``` cpp
-basic_string<charT, traits, Allocator> str() const;
 ```
-*Returns:* `rdbuf()->str()`.
 ``` cpp
-void str(const basic_string<charT, traits, Allocator>& str);
 ```
-*Effects:* Calls `rdbuf()->str(str)`.
 ## File-based streams <a id="file.streams">[[file.streams]]</a>
 ### Header `<fstream>` synopsis <a id="fstream.syn">[[fstream.syn]]</a>
@@ -5054,13 +5625,13 @@ files.
 or sink of bytes. In an environment that uses a large character set, the
 file typically holds multibyte character sequences and the
 `basic_filebuf` object converts those multibyte sequences into wide
 character sequences. — *end note*]
-In this subclause, member functions taking arguments of
 `const filesystem::path::value_type*` are only be provided on systems
-where `filesystem::path::value_type` ([[fs.class.path]]) is not `char`.
 [*Note 2*: These functions enable class `path` support for systems with
 a wide native path character type, such as `wchar_t`. — *end note*]
 ### Class template `basic_filebuf` <a id="filebuf">[[filebuf]]</a>
@@ -5076,16 +5647,16 @@ namespace std {
     using off_type    = typename traits::off_type;
     using traits_type = traits;
     // [filebuf.cons], constructors/destructor
     basic_filebuf();
-    basic_filebuf(const basic_filebuf& rhs) = delete;
     basic_filebuf(basic_filebuf&& rhs);
     virtual ~basic_filebuf();
     // [filebuf.assign], assign and swap
-    basic_filebuf& operator=(const basic_filebuf& rhs) = delete;
     basic_filebuf& operator=(basic_filebuf&& rhs);
     void swap(basic_filebuf& rhs);
     // [filebuf.members], members
     bool is_open() const;
@@ -5143,45 +5714,44 @@ An instance of `basic_filebuf` behaves as described in  [[filebuf]]
 provided `traits::pos_type` is `fpos<traits::{}state_type>`. Otherwise
 the behavior is undefined.
 In order to support file I/O and multibyte/wide character conversion,
 conversions are performed using members of a facet, referred to as
-`a_codecvt` in following sections, obtained as if by
 ``` cpp
 const codecvt<charT, char, typename traits::state_type>& a_codecvt =
   use_facet<codecvt<charT, char, typename traits::state_type>>(getloc());
 ```
-#### `basic_filebuf` constructors <a id="filebuf.cons">[[filebuf.cons]]</a>
 ``` cpp
 basic_filebuf();
 ```
-*Effects:* Constructs an object of class `basic_filebuf<charT, traits>`,
-initializing the base class with
-`basic_streambuf<charT, traits>()` ([[streambuf.cons]]).
-*Postconditions:* `is_open() == false`.
 ``` cpp
 basic_filebuf(basic_filebuf&& rhs);
 ```
-*Effects:* Move constructs from the rvalue `rhs`. It is
-*implementation-defined* whether the sequence pointers in `*this`
-(`eback()`, `gptr()`, `egptr()`, `pbase()`, `pptr()`, `epptr()`) obtain
-the values which `rhs` had. Whether they do or not, `*this` and `rhs`
-reference separate buffers (if any at all) after the construction.
-Additionally `*this` references the file which `rhs` did before the
-construction, and `rhs` references no file after the construction. The
-openmode, locale and any other state of `rhs` is also copied.
-*Postconditions:* Let `rhs_p` refer to the state of `rhs` just prior to
-this construction and let `rhs_a` refer to the state of `rhs` just after
-this construction.
 - `is_open() == rhs_p.is_open()`
 - `rhs_a.is_open() == false`
 - `gptr() - eback() == rhs_p.gptr() - rhs_p.eback()`
 - `egptr() - eback() == rhs_p.egptr() - rhs_p.eback()`
@@ -5196,16 +5766,16 @@ this construction.
 ``` cpp
 virtual ~basic_filebuf();
 ```
-*Effects:* Destroys an object of class `basic_filebuf<charT, traits>`.
-Calls `close()`. If an exception occurs during the destruction of the
-object, including the call to `close()`, the exception is caught but not
-rethrown (see  [[res.on.exception.handling]]).
-#### Assign and swap <a id="filebuf.assign">[[filebuf.assign]]</a>
 ``` cpp
 basic_filebuf& operator=(basic_filebuf&& rhs);
 ```
@@ -5225,11 +5795,11 @@ void swap(basic_filebuf& rhs);
 template<class charT, class traits>
   void swap(basic_filebuf<charT, traits>& x,
             basic_filebuf<charT, traits>& y);
 ```
-*Effects:* As if by `x.swap(y)`.
 #### Member functions <a id="filebuf.members">[[filebuf.members]]</a>
 ``` cpp
 bool is_open() const;
@@ -5242,19 +5812,20 @@ non-null value) and there has been no intervening call to close.
 basic_filebuf* open(const char* s, ios_base::openmode mode);
 basic_filebuf* open(const filesystem::path::value_type* s,
                     ios_base::openmode mode);  // wide systems only; see [fstream.syn]
 ```
 *Effects:* If `is_open() != false`, returns a null pointer. Otherwise,
-initializes the `filebuf` as required. It then opens a file, if
-possible, whose name is the NTBS`s` (as if by calling
-`fopen(s, modstr)`). The NTBS`modstr` is determined from
-`mode & ~ios_base::ate` as indicated in
-Table  [[tab:iostreams.file.open.modes]]. If `mode` is not some
-combination of flags shown in the table then the open fails.
-**Table: File open modes** <a id="tab:iostreams.file.open.modes">[tab:iostreams.file.open.modes]</a>
 | `binary` | `in` | `out` | `trunc` | `app` |     | `stdio` equivalent |
 | -------- | ---- | ----- | ------- | ----- | --- | ------------------ |
 |          |      | +     |         |       | `"w"` |
 |          |      | +     |         | +     | `"a"` |
@@ -5273,13 +5844,14 @@ combination of flags shown in the table then the open fails.
 | +        | +    | +     | +       |       | `"w+b"` |
 | +        | +    | +     |         | +     | `"a+b"` |
 | +        | +    |       |         | +     | `"a+b"` |
-If the open operation succeeds and `(mode & ios_base::ate) != 0`,
 positions the file to the end (as if by calling
-`fseek(file, 0, SEEK_END)`).[^40]
 If the repositioning operation fails, calls `close()` and returns a null
 pointer to indicate failure.
 *Returns:* `this` if successful, a null pointer otherwise.
@@ -5308,20 +5880,20 @@ or throws an exception, the function closes the file (as if by calling
 these calls throws an exception, the exception is caught and rethrown
 after closing the file.
 *Returns:* `this` on success, a null pointer otherwise.
-*Postconditions:* `is_open() == false`.
 #### Overridden virtual functions <a id="filebuf.virtuals">[[filebuf.virtuals]]</a>
 ``` cpp
 streamsize showmanyc() override;
 ```
-*Effects:* Behaves the same as
-`basic_streambuf::showmanyc()` ([[streambuf.virtuals]]).
 *Remarks:* An implementation might well provide an overriding definition
 for this function signature if it can determine that more characters can
 be read from the input sequence.
@@ -5378,11 +5950,11 @@ sequence, if possible, in one of three ways:
   either the input sequence has a putback position available or the
   function makes a putback position available, decrements the next
   pointer for the input sequence, `gptr()`. Returns:
   `traits::not_eof(c)`.
-*Returns:* `traits::eof()` to indicate failure.
 *Remarks:* If `is_open() == false`, the function always fails.
 The function does not put back a character directly to the input
 sequence.
@@ -5452,13 +6024,13 @@ and write any unshift sequence. Next, seek to the new position: if
 operation was overflow or the put buffer is non-empty. “Write any
 unshift sequence” means, if `width` if less than zero then call
 `a_codecvt.unshift(state, xbuf, xbuf+XSIZE, xbuf_end)` and output the
 resulting unshift sequence. The function determines one of three values
 for the argument `whence`, of type `int`, as indicated in
-Table  [[tab:iostreams.seekoff.effects]].
-**Table: `seekoff` effects** <a id="tab:iostreams.seekoff.effects">[tab:iostreams.seekoff.effects]</a>
 | `way` Value      | `stdio` Equivalent |
 | ---------------- | ------------------ |
 | `basic_ios::beg` | `SEEK_SET`         |
 | `basic_ios::cur` | `SEEK_CUR`         |
@@ -5507,13 +6079,13 @@ characters to the file, then flushes the file as if by calling
 ``` cpp
 void imbue(const locale& loc) override;
 ```
-*Requires:* If the file is not positioned at its beginning and the
 encoding of the current locale as determined by `a_codecvt.encoding()`
-is state-dependent ([[locale.codecvt.virtuals]]) then that facet is the
 same as the corresponding facet of `loc`.
 *Effects:* Causes characters inserted or extracted after this call to be
 converted according to `loc` until another call of `imbue`.
@@ -5542,15 +6114,15 @@ namespace std {
                             ios_base::openmode mode = ios_base::in);// wide systems only; see [fstream.syn]
     explicit basic_ifstream(const string& s,
                             ios_base::openmode mode = ios_base::in);
     explicit basic_ifstream(const filesystem::path& s,
                             ios_base::openmode mode = ios_base::in);
-    basic_ifstream(const basic_ifstream& rhs) = delete;
     basic_ifstream(basic_ifstream&& rhs);
     // [ifstream.assign], assign and swap
-    basic_ifstream& operator=(const basic_ifstream& rhs) = delete;
     basic_ifstream& operator=(basic_ifstream&& rhs);
     void swap(basic_ifstream& rhs);
     // [ifstream.members], members
     basic_filebuf<charT, traits>* rdbuf() const;
@@ -5577,62 +6149,52 @@ files. It uses a `basic_filebuf<{}charT, traits>` object to control the
 associated sequence. For the sake of exposition, the maintained data is
 presented here as:
 - `sb`, the `filebuf` object.
-#### `basic_ifstream` constructors <a id="ifstream.cons">[[ifstream.cons]]</a>
 ``` cpp
 basic_ifstream();
 ```
-*Effects:* Constructs an object of class
-`basic_ifstream<charT, traits>`, initializing the base class with
-`basic_istream(&sb)` and initializing `sb` with
-`basic_filebuf<charT, traits>())` ([[istream.cons]], [[filebuf.cons]]).
 ``` cpp
 explicit basic_ifstream(const char* s,
                         ios_base::openmode mode = ios_base::in);
 explicit basic_ifstream(const filesystem::path::value_type* s,
                         ios_base::openmode mode = ios_base::in);  // wide systems only; see [fstream.syn]
 ```
-*Effects:* Constructs an object of class `basic_ifstream`, initializing
-the base class with `basic_istream(&sb)` and initializing `sb` with
-`basic_filebuf<charT, traits>())` ([[istream.cons]], [[filebuf.cons]]),
-then calls `rdbuf()->open(s, mode | ios_base::in)`. If that function
-returns a null pointer, calls `setstate(failbit)`.
 ``` cpp
 explicit basic_ifstream(const string& s,
                         ios_base::openmode mode = ios_base::in);
 explicit basic_ifstream(const filesystem::path& s,
                         ios_base::openmode mode = ios_base::in);
 ```
-*Effects:* The same as `basic_ifstream(s.c_str(), mode)`.
 ``` cpp
 basic_ifstream(basic_ifstream&& rhs);
 ```
-*Effects:* Move constructs from the rvalue `rhs`. This is accomplished
-by move constructing the base class, and the contained `basic_filebuf`.
-Next `basic_istream<charT, traits>::set_rdbuf(&sb)` is called to install
-the contained `basic_filebuf`.
-#### Assign and swap <a id="ifstream.assign">[[ifstream.assign]]</a>
-``` cpp
-basic_ifstream& operator=(basic_ifstream&& rhs);
-```
-*Effects:* Move assigns the base and members of `*this` from the base
-and corresponding members of `rhs`.
-*Returns:* `*this`.
 ``` cpp
 void swap(basic_ifstream& rhs);
 ```
@@ -5643,19 +6205,19 @@ void swap(basic_ifstream& rhs);
 template<class charT, class traits>
   void swap(basic_ifstream<charT, traits>& x,
             basic_ifstream<charT, traits>& y);
 ```
-*Effects:* As if by `x.swap(y)`.
 #### Member functions <a id="ifstream.members">[[ifstream.members]]</a>
 ``` cpp
 basic_filebuf<charT, traits>* rdbuf() const;
 ```
-*Returns:* `const_cast<basic_filebuf<charT, traits>*>(&sb)`.
 ``` cpp
 bool is_open() const;
 ```
@@ -5667,12 +6229,12 @@ void open(const filesystem::path::value_type* s,
           ios_base::openmode mode = ios_base::in);  // wide systems only; see [fstream.syn]
 ```
 *Effects:* Calls `rdbuf()->open(s, mode | ios_base::in)`. If that
 function does not return a null pointer calls `clear()`, otherwise calls
-`setstate(failbit)` (which may throw `ios_base::failure`)
-([[iostate.flags]]).
 ``` cpp
 void open(const string& s, ios_base::openmode mode = ios_base::in);
 void open(const filesystem::path& s, ios_base::openmode mode = ios_base::in);
 ```
@@ -5683,11 +6245,11 @@ void open(const filesystem::path& s, ios_base::openmode mode = ios_base::in);
 void close();
 ```
 *Effects:* Calls `rdbuf()->close()` and, if that function returns a null
 pointer, calls `setstate(failbit)` (which may throw
-`ios_base::failure`) ([[iostate.flags]]).
 ### Class template `basic_ofstream` <a id="ofstream">[[ofstream]]</a>
 ``` cpp
 namespace std {
@@ -5702,21 +6264,21 @@ namespace std {
     // [ofstream.cons], constructors
     basic_ofstream();
     explicit basic_ofstream(const char* s,
                             ios_base::openmode mode = ios_base::out);
-    explicit basic_ofstream(const filesystem::path::value_type* s,
-                            ios_base::openmode mode = ios_base::out);  // wide systems only; see [fstream.syn]
     explicit basic_ofstream(const string& s,
                             ios_base::openmode mode = ios_base::out);
     explicit basic_ofstream(const filesystem::path& s,
                             ios_base::openmode mode = ios_base::out);
-    basic_ofstream(const basic_ofstream& rhs) = delete;
     basic_ofstream(basic_ofstream&& rhs);
     // [ofstream.assign], assign and swap
-    basic_ofstream& operator=(const basic_ofstream& rhs) = delete;
     basic_ofstream& operator=(basic_ofstream&& rhs);
     void swap(basic_ofstream& rhs);
     // [ofstream.members], members
     basic_filebuf<charT, traits>* rdbuf() const;
@@ -5743,63 +6305,52 @@ files. It uses a `basic_filebuf<{}charT, traits>` object to control the
 associated sequence. For the sake of exposition, the maintained data is
 presented here as:
 - `sb`, the `filebuf` object.
-#### `basic_ofstream` constructors <a id="ofstream.cons">[[ofstream.cons]]</a>
 ``` cpp
 basic_ofstream();
 ```
-*Effects:* Constructs an object of class
-`basic_ofstream<charT, traits>`, initializing the base class with
-`basic_ostream(&sb)` and initializing `sb` with
-`basic_filebuf<charT, traits>())` ([[ostream.cons]], [[filebuf.cons]]).
 ``` cpp
 explicit basic_ofstream(const char* s,
                         ios_base::openmode mode = ios_base::out);
 explicit basic_ofstream(const filesystem::path::value_type* s,
                         ios_base::openmode mode = ios_base::out); // wide systems only; see [fstream.syn]
 ```
-*Effects:* Constructs an object of class
-`basic_ofstream<charT, traits>`, initializing the base class with
-`basic_ostream(&sb)` and initializing `sb` with
-`basic_filebuf<charT, traits>())` ([[ostream.cons]], [[filebuf.cons]]),
-then calls `rdbuf()->open(s, mode | ios_base::out)`. If that function
-returns a null pointer, calls `setstate(failbit)`.
 ``` cpp
 explicit basic_ofstream(const string& s,
                         ios_base::openmode mode = ios_base::out);
 explicit basic_ofstream(const filesystem::path& s,
                         ios_base::openmode mode = ios_base::out);
 ```
-*Effects:* The same as `basic_ofstream(s.c_str(), mode)`.
 ``` cpp
 basic_ofstream(basic_ofstream&& rhs);
 ```
-*Effects:* Move constructs from the rvalue `rhs`. This is accomplished
-by move constructing the base class, and the contained `basic_filebuf`.
-Next `basic_ostream<charT, traits>::set_rdbuf(&sb)` is called to install
-the contained `basic_filebuf`.
-#### Assign and swap <a id="ofstream.assign">[[ofstream.assign]]</a>
-``` cpp
-basic_ofstream& operator=(basic_ofstream&& rhs);
-```
-*Effects:* Move assigns the base and members of `*this` from the base
-and corresponding members of `rhs`.
-*Returns:* `*this`.
 ``` cpp
 void swap(basic_ofstream& rhs);
 ```
@@ -5810,19 +6361,19 @@ void swap(basic_ofstream& rhs);
 template<class charT, class traits>
   void swap(basic_ofstream<charT, traits>& x,
             basic_ofstream<charT, traits>& y);
 ```
-*Effects:* As if by `x.swap(y)`.
 #### Member functions <a id="ofstream.members">[[ofstream.members]]</a>
 ``` cpp
 basic_filebuf<charT, traits>* rdbuf() const;
 ```
-*Returns:* `const_cast<basic_filebuf<charT, traits>*>(&sb)`.
 ``` cpp
 bool is_open() const;
 ```
@@ -5834,20 +6385,20 @@ void open(const filesystem::path::value_type* s,
           ios_base::openmode mode = ios_base::out);             // wide systems only; see [fstream.syn]
 ```
 *Effects:* Calls `rdbuf()->open(s, mode | ios_base::out)`. If that
 function does not return a null pointer calls `clear()`, otherwise calls
-`setstate(failbit)` (which may throw `ios_base::failure`)
-([[iostate.flags]]).
 ``` cpp
 void close();
 ```
 *Effects:* Calls `rdbuf()->close()` and, if that function fails (returns
 a null pointer), calls `setstate(failbit)` (which may throw
-`ios_base::failure`) ([[iostate.flags]]).
 ``` cpp
 void open(const string& s, ios_base::openmode mode = ios_base::out);
 void open(const filesystem::path& s, ios_base::openmode mode = ios_base::out);
 ```
@@ -5871,34 +6422,34 @@ namespace std {
     basic_fstream();
     explicit basic_fstream(
       const char* s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
     explicit basic_fstream(
-      const std::filesystem::path::value_type* s,
       ios_base::openmode mode = ios_base::in|ios_base::out);    // wide systems only; see [fstream.syn]
     explicit basic_fstream(
       const string& s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
     explicit basic_fstream(
       const filesystem::path& s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
-    basic_fstream(const basic_fstream& rhs) = delete;
     basic_fstream(basic_fstream&& rhs);
     // [fstream.assign], assign and swap
-    basic_fstream& operator=(const basic_fstream& rhs) = delete;
     basic_fstream& operator=(basic_fstream&& rhs);
     void swap(basic_fstream& rhs);
     // [fstream.members], members
     basic_filebuf<charT, traits>* rdbuf() const;
     bool is_open() const;
     void open(
       const char* s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
     void open(
-      const std::filesystem::path::value_type* s,
       ios_base::openmode mode = ios_base::in|ios_base::out);    // wide systems only; see [fstream.syn]
     void open(
       const string& s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
     void open(
@@ -5921,18 +6472,18 @@ writing from named files. It uses a `basic_filebuf<charT, traits>`
 object to control the associated sequences. For the sake of exposition,
 the maintained data is presented here as:
 - `sb`, the `basic_filebuf` object.
-#### `basic_fstream` constructors <a id="fstream.cons">[[fstream.cons]]</a>
 ``` cpp
 basic_fstream();
 ```
-*Effects:* Constructs an object of class `basic_fstream<charT, traits>`,
-initializing the base class with `basic_iostream(&sb)` and initializing
 `sb` with `basic_filebuf<charT, traits>()`.
 ``` cpp
 explicit basic_fstream(
   const char* s,
@@ -5940,12 +6491,12 @@ explicit basic_fstream(
 explicit basic_fstream(
   const filesystem::path::value_type* s,
   ios_base::openmode mode = ios_base::in | ios_base::out);  // wide systems only; see [fstream.syn]
 ```
-*Effects:* Constructs an object of class `basic_fstream<charT, traits>`,
-initializing the base class with `basic_iostream(&sb)` and initializing
 `sb` with `basic_filebuf<charT, traits>()`. Then calls
 `rdbuf()->open(s, mode)`. If that function returns a null pointer, calls
 `setstate(failbit)`.
 ``` cpp
@@ -5955,31 +6506,22 @@ explicit basic_fstream(
 explicit basic_fstream(
   const filesystem::path& s,
   ios_base::openmode mode = ios_base::in | ios_base::out);
 ```
-*Effects:* The same as `basic_fstream(s.c_str(), mode)`.
 ``` cpp
 basic_fstream(basic_fstream&& rhs);
 ```
-*Effects:* Move constructs from the rvalue `rhs`. This is accomplished
-by move constructing the base class, and the contained `basic_filebuf`.
-Next `basic_istream<charT, traits>::set_rdbuf(&sb)` is called to install
-the contained `basic_filebuf`.
-#### Assign and swap <a id="fstream.assign">[[fstream.assign]]</a>
-``` cpp
-basic_fstream& operator=(basic_fstream&& rhs);
-```
-*Effects:* Move assigns the base and members of `*this` from the base
-and corresponding members of `rhs`.
-*Returns:* `*this`.
 ``` cpp
 void swap(basic_fstream& rhs);
 ```
@@ -5990,19 +6532,19 @@ void swap(basic_fstream& rhs);
 template<class charT, class traits>
   void swap(basic_fstream<charT, traits>& x,
             basic_fstream<charT, traits>& y);
 ```
-*Effects:* As if by `x.swap(y)`.
 #### Member functions <a id="fstream.members">[[fstream.members]]</a>
 ``` cpp
 basic_filebuf<charT, traits>* rdbuf() const;
 ```
-*Returns:* `const_cast<basic_filebuf<charT, traits>*>(&sb)`.
 ``` cpp
 bool is_open() const;
 ```
@@ -6018,11 +6560,11 @@ void open(
 ```
 *Effects:* Calls `rdbuf()->open(s, mode)`. If that function does not
 return a null pointer calls `clear()`, otherwise calls
 `setstate(failbit)` (which may throw
-`ios_base::failure`) ([[iostate.flags]]).
 ``` cpp
 void open(
   const string& s,
   ios_base::openmode mode = ios_base::in | ios_base::out);
@@ -6037,41 +6579,489 @@ void open(
 void close();
 ```
 *Effects:* Calls `rdbuf()->close()` and, if that function returns a null
 pointer, calls `setstate(failbit)` (which may throw
-`ios_base::failure`) ([[iostate.flags]]).
 ## File systems <a id="filesystems">[[filesystems]]</a>
 ### General <a id="fs.general">[[fs.general]]</a>
-This subclause describes operations on file systems and their
-components, such as paths, regular files, and directories.
 ### Conformance <a id="fs.conformance">[[fs.conformance]]</a>
 Conformance is specified in terms of behavior. Ideal behavior is not
 always implementable, so the conformance subclauses take that into
 account.
 #### POSIX conformance <a id="fs.conform.9945">[[fs.conform.9945]]</a>
-Some behavior is specified by reference to POSIX ([[fs.norm.ref]]). How
 such behavior is actually implemented is unspecified.
 [*Note 1*: This constitutes an “as if” rule allowing implementations to
 call native operating system or other APIs. — *end note*]
-Implementations are encouraged to provide such behavior as it is defined
-by POSIX. Implementations shall document any behavior that differs from
-the behavior defined by POSIX. Implementations that do not support exact
-POSIX behavior are encouraged to provide behavior as close to POSIX
-behavior as is reasonable given the limitations of actual operating
-systems and file systems. If an implementation cannot provide any
-reasonable behavior, the implementation shall report an error as
-specified in  [[fs.err.report]].
 [*Note 2*: This allows users to rely on an exception being thrown or an
 error code being set when an implementation cannot provide any
 reasonable behavior. — *end note*]
@@ -6084,225 +7074,88 @@ other features of more capable file systems, so implementations are not
 required to support those features on the FAT file system but instead
 are required to report an error as described above. — *end example*]
 #### Operating system dependent behavior conformance <a id="fs.conform.os">[[fs.conform.os]]</a>
-Some behavior is specified as being operating system dependent (
-[[fs.def.osdep]]). The operating system an implementation is dependent
-upon is *implementation-defined*.
 It is permissible for an implementation to be dependent upon an
 operating system emulator rather than the actual underlying operating
 system.
 #### File system race behavior <a id="fs.race.behavior">[[fs.race.behavior]]</a>
-Behavior is undefined if calls to functions provided by this subclause
-introduce a file system race ([[fs.def.race]]).
 If the possibility of a file system race would make it unreliable for a
 program to test for a precondition before calling a function described
-herein, *Requires:* is not specified for the function.
 [*Note 1*: As a design practice, preconditions are not specified when
 it is unreasonable for a program to detect them prior to calling the
 function. — *end note*]
 ### Normative references <a id="fs.norm.ref">[[fs.norm.ref]]</a>
-This subclause mentions commercially available operating systems for
-purposes of exposition.[^41]
-### Terms and definitions <a id="fs.definitions">[[fs.definitions]]</a>
-A path that unambiguously identifies the location of a file without
-reference to an additional starting location. The elements of a path
-that determine if it is absolute are operating system dependent.
-A file within a file system that acts as a container of directory
-entries that contain information about other files, possibly including
-other directory files.
-An object within a file system that holds user or system data. Files can
-be written to, or read from, or both. A file has certain attributes,
-including type. File types include regular files and directories. Other
-types of files, such as symbolic links ([[fs.def.symlink]]), may be
-supported by the implementation.
-A collection of files and their attributes.
-The condition that occurs when multiple threads, processes, or computers
-interleave access and modification of the same object within a file
-system.
-The name of a file. Filenames *dot* and *dot-dot*, consisting solely of
-one and two period characters respectively, have special meaning. The
-following characteristics of filenames are operating system dependent:
-- The permitted characters. \[*Example 1*: Some operating systems
-  prohibit the ASCII control characters (0x00 – 0x1F) in
-  filenames. — *end example*]
-- The maximum permitted length.
-- Filenames that are not permitted.
-- Filenames that have special meaning.
-- Case awareness and sensitivity during path resolution.
-- Special rules that may apply to file types other than regular files,
-  such as directories.
-A link ([[fs.def.link]]) to an existing file. Some file systems support
-multiple hard links to a file. If the last hard link to a file is
-removed, the file itself is removed.
-[*Note 1*: A hard link can be thought of as a shared-ownership smart
-pointer to a file. — *end note*]
-An object that associates a filename with a file. Several links can
-associate names with the same file.
-For narrow character strings, the operating system dependent current
-encoding for pathnames ([[fs.def.pathname]]). For wide character
-strings, the implementation-defined execution wide-character set
-encoding ([[lex.charset]]).
-The operating system dependent pathname format accepted by the host
-operating system.
-A path in normal form is said to be *normalized*. The process of
-obtaining a normalized path from a path that is not in normal form is
-called *normalization*.
-Normalization of a generic format pathname means:
-1.  If the path is empty, stop.
-2.  Replace each slash character in the *root-name* with a
-    *preferred-separator*.
-3.  Replace each *directory-separator* with a *preferred-separator*.
-    \[*Note 2*: The generic pathname grammar ([[fs.path.generic]])
-    defines *directory-separator* as one or more slashes and
-    *preferred-separator*s. — *end note*]
-4.  Remove each *dot* filename and any immediately following
-    *directory-separator*.
-5.  As long as any appear, remove a non-*dot-dot* filename immediately
-    followed by a *directory-separator* and a *dot-dot* filename, along
-    with any immediately following *directory-separator*.
-6.  If there is a *root-directory*, remove all *dot-dot* filenames and
-    any *directory-separator*s immediately following them.
-    \[*Note 3*: These *dot-dot* filenames attempt to refer to
-    nonexistent parent directories. — *end note*]
-7.  If the last filename is *dot-dot*, remove any trailing
-    *directory-separator*.
-8.  If the path is empty, add a *dot*.
-Behavior that is dependent upon the behavior and characteristics of an
-operating system. See  [[fs.conform.os]].
-the directory that both contains a directory entry for the given
-directory and is represented by the filename *dot-dot* in the given
-directory.
-a directory containing a directory entry for the file under discussion.
-A sequence of elements that identify the location of a file within a
-filesystem. The elements are the *root-name*ₒₚₜ , *root-directory*ₒₚₜ ,
-and an optional sequence of filenames. The maximum number of elements in
-the sequence is operating system dependent.
-A character string that represents the name of a path. Pathnames are
-formatted according to the generic pathname format grammar (
-[[fs.path.generic]]) or an operating system dependent native pathname
-format.
-Pathname resolution is the operating system dependent mechanism for
-resolving a pathname to a particular file in a file hierarchy. There may
-be multiple pathnames that resolve to the same file.
-[*Example 2*: POSIX specifies the mechanism in section 4.11, Pathname
-resolution. — *end example*]
-A path that is not absolute, and as such, only unambiguously identifies
-the location of a file when resolved ([[fs.def.pathres]]) relative to
-an implied starting location. The elements of a path that determine if
-it is relative are operating system dependent.
-[*Note 4*: Pathnames “.” and “..” are relative paths. — *end note*]
-A type of file with the property that when the file is encountered
-during pathname resolution, a string stored by the file is used to
-modify the pathname resolution.
-[*Note 5*: Symbolic links are often called symlinks. A symbolic link
-can be thought of as a raw pointer to a file. If the file pointed to
-does not exist, the symbolic link is said to be a “dangling” symbolic
-link. — *end note*]
 ### Requirements <a id="fs.req">[[fs.req]]</a>
-Throughout this subclause, `char`, `wchar_t`, `char16_t`, and `char32_t`
-are collectively called *encoded character types*.
 Functions with template parameters named `EcharT` shall not participate
 in overload resolution unless `EcharT` is one of the encoded character
 types.
-Template parameters named `InputIterator` shall meet the input iterator
-requirements ([[input.iterators]]) and shall have a value type that is
-one of the encoded character types.
 [*Note 1*: Use of an encoded character type implies an associated
 character set and encoding. Since `signed char` and `unsigned char` have
 no implied character set and encoding, they are not included as
 permitted types. — *end note*]
-Template parameters named `Allocator` shall meet the Allocator
-requirements ([[allocator.requirements]]).
 #### Namespaces and headers <a id="fs.req.namespace">[[fs.req.namespace]]</a>
-Unless otherwise specified, references to entities described in this
-subclause are assumed to be qualified with `::std::filesystem::`.
 ### Header `<filesystem>` synopsis <a id="fs.filesystem.syn">[[fs.filesystem.syn]]</a>
 ``` cpp
 namespace std::filesystem {
   // [fs.class.path], paths
   class path;
   // [fs.path.nonmember], path non-member functions
   void swap(path& lhs, path& rhs) noexcept;
   size_t hash_value(const path& p) noexcept;
- bool operator==(const path& lhs, const path& rhs) noexcept;
-  bool operator!=(const path& lhs, const path& rhs) noexcept;
-  bool operator< (const path& lhs, const path& rhs) noexcept;
-  bool operator<=(const path& lhs, const path& rhs) noexcept;
-  bool operator> (const path& lhs, const path& rhs) noexcept;
-  bool operator>=(const path& lhs, const path& rhs) noexcept;
-  path operator/ (const path& lhs, const path& rhs);
-  // [fs.path.io], path inserter and extractor
-  template <class charT, class traits>
-    basic_ostream<charT, traits>&
-      operator<<(basic_ostream<charT, traits>& os, const path& p);
-  template <class charT, class traits>
-    basic_istream<charT, traits>&
-      operator>>(basic_istream<charT, traits>& is, path& p);
-  // [fs.path.factory], path factory functions
-  template <class Source>
-    path u8path(const Source& source);
-  template <class InputIterator>
-    path u8path(InputIterator first, InputIterator last);
-  // [fs.class.filesystem_error], filesystem errors
   class filesystem_error;
-  // [fs.class.directory_entry], directory entries
   class directory_entry;
-  // [fs.class.directory_iterator], directory iterators
   class directory_iterator;
   // [fs.dir.itr.nonmembers], range access for directory iterators
   directory_iterator begin(directory_iterator iter) noexcept;
   directory_iterator end(const directory_iterator&) noexcept;
@@ -6312,53 +7165,55 @@ namespace std::filesystem {
   // [fs.rec.dir.itr.nonmembers], range access for recursive directory iterators
   recursive_directory_iterator begin(recursive_directory_iterator iter) noexcept;
   recursive_directory_iterator end(const recursive_directory_iterator&) noexcept;
-  // [fs.class.file_status], file status
   class file_status;
   struct space_info {
     uintmax_t capacity;
     uintmax_t free;
     uintmax_t available;
   };
   // [fs.enum], enumerations
   enum class file_type;
   enum class perms;
   enum class perm_options;
   enum class copy_options;
   enum class directory_options;
-  using file_time_type = chrono::time_point<trivial-clock>;
   // [fs.op.funcs], filesystem operations
-  path absolute(const path& p, const path& base = current_path());
-  path canonical(const path& p, const path& base = current_path());
   path canonical(const path& p, error_code& ec);
-  path canonical(const path& p, const path& base, error_code& ec);
   void copy(const path& from, const path& to);
-  void copy(const path& from, const path& to, error_code& ec) noexcept;
   void copy(const path& from, const path& to, copy_options options);
   void copy(const path& from, const path& to, copy_options options,
-            error_code& ec) noexcept;
   bool copy_file(const path& from, const path& to);
-  bool copy_file(const path& from, const path& to, error_code& ec) noexcept;
   bool copy_file(const path& from, const path& to, copy_options option);
   bool copy_file(const path& from, const path& to, copy_options option,
-                 error_code& ec) noexcept;
   void copy_symlink(const path& existing_symlink, const path& new_symlink);
   void copy_symlink(const path& existing_symlink, const path& new_symlink,
                     error_code& ec) noexcept;
   bool create_directories(const path& p);
-  bool create_directories(const path& p, error_code& ec) noexcept;
   bool create_directory(const path& p);
   bool create_directory(const path& p, error_code& ec) noexcept;
   bool create_directory(const path& p, const path& attributes);
@@ -6380,17 +7235,17 @@ namespace std::filesystem {
   path current_path();
   path current_path(error_code& ec);
   void current_path(const path& p);
   void current_path(const path& p, error_code& ec) noexcept;
   bool exists(file_status s) noexcept;
   bool exists(const path& p);
   bool exists(const path& p, error_code& ec) noexcept;
-  bool equivalent(const path& p1, const path& p2);
-  bool equivalent(const path& p1, const path& p2, error_code& ec) noexcept;
   uintmax_t file_size(const path& p);
   uintmax_t file_size(const path& p, error_code& ec) noexcept;
   uintmax_t hard_link_count(const path& p);
   uintmax_t hard_link_count(const path& p, error_code& ec) noexcept;
@@ -6406,11 +7261,11 @@ namespace std::filesystem {
   bool is_directory(file_status s) noexcept;
   bool is_directory(const path& p);
   bool is_directory(const path& p, error_code& ec) noexcept;
   bool is_empty(const path& p);
-  bool is_empty(const path& p, error_code& ec) noexcept;
   bool is_fifo(file_status s) noexcept;
   bool is_fifo(const path& p);
   bool is_fifo(const path& p, error_code& ec) noexcept;
@@ -6453,11 +7308,11 @@ namespace std::filesystem {
   bool remove(const path& p);
   bool remove(const path& p, error_code& ec) noexcept;
   uintmax_t remove_all(const path& p);
-  uintmax_t remove_all(const path& p, error_code& ec) noexcept;
   void rename(const path& from, const path& to);
   void rename(const path& from, const path& to, error_code& ec) noexcept;
   void resize_file(const path& p, uintmax_t size);
@@ -6480,15 +7335,13 @@ namespace std::filesystem {
   path weakly_canonical(const path& p);
   path weakly_canonical(const path& p, error_code& ec);
 }
 ```
-`trivial-clock` is an *implementation-defined* type that satisfies the
-`TrivialClock` requirements ([[time.clock.req]]) and that is capable of
-representing and measuring file time values. Implementations should
-ensure that the resolution and range of `file_time_type` reflect the
-operating system dependent resolution and range of file time values.
 ### Error reporting <a id="fs.err.report">[[fs.err.report]]</a>
 Filesystem library functions often provide two overloads, one that
 throws an exception to report file system errors, and another that sets
@@ -6534,22 +7387,49 @@ follows, unless otherwise specified:
   appropriate for the specific operating system dependent error.
   Otherwise, `clear()` is called on the `error_code&` argument.
 ### Class `path` <a id="fs.class.path">[[fs.class.path]]</a>
-An object of class `path` represents a path ([[fs.def.path]]) and
-contains a pathname ([[fs.def.pathname]]). Such an object is concerned
-only with the lexical and syntactic aspects of a path. The path does not
-necessarily exist in external storage, and the pathname is not
-necessarily valid for the current operating system or for a particular
-file system.
 [*Note 1*: Class `path` is used to support the differences between the
 string types used by different operating systems to represent pathnames,
 and to perform conversions between encodings when
 necessary. — *end note*]
 ``` cpp
 namespace std::filesystem {
   class path {
   public:
     using value_type  = see below;
@@ -6580,11 +7460,11 @@ namespace std::filesystem {
     path& operator=(string_type&& source);
     path& assign(string_type&& source);
     template<class Source>
       path& operator=(const Source& source);
     template<class Source>
-      path& assign(const Source& source)
     template<class InputIterator>
       path& assign(InputIterator first, InputIterator last);
     // [fs.path.append], appends
     path& operator/=(const path& p);
@@ -6616,10 +7496,16 @@ namespace std::filesystem {
     path& remove_filename();
     path& replace_filename(const path& replacement);
     path& replace_extension(const path& replacement = path());
     void  swap(path& rhs) noexcept;
     // [fs.path.native.obs], native format observers
     const string_type& native() const noexcept;
     const value_type*  c_str() const noexcept;
     operator string_type() const;
@@ -6627,22 +7513,22 @@ namespace std::filesystem {
              class Allocator = allocator<EcharT>>
       basic_string<EcharT, traits, Allocator>
         string(const Allocator& a = Allocator()) const;
     std::string    string() const;
     std::wstring   wstring() const;
-    std::string    u8string() const;
     std::u16string u16string() const;
     std::u32string u32string() const;
     // [fs.path.generic.obs], generic format observers
     template<class EcharT, class traits = char_traits<EcharT>,
              class Allocator = allocator<EcharT>>
       basic_string<EcharT, traits, Allocator>
         generic_string(const Allocator& a = Allocator()) const;
     std::string    generic_string() const;
     std::wstring   generic_wstring() const;
-    std::string    generic_u8string() const;
     std::u16string generic_u16string() const;
     std::u32string generic_u32string() const;
     // [fs.path.compare], compare
     int compare(const path& p) const noexcept;
@@ -6659,11 +7545,11 @@ namespace std::filesystem {
     path filename() const;
     path stem() const;
     path extension() const;
     // [fs.path.query], query
-    bool empty() const noexcept;
     bool has_root_name() const;
     bool has_root_directory() const;
     bool has_root_path() const;
     bool has_relative_path() const;
     bool has_parent_path() const;
@@ -6682,21 +7568,29 @@ namespace std::filesystem {
     class iterator;
     using const_iterator = iterator;
     iterator begin() const;
     iterator end() const;
   };
 }
 ```
 `value_type` is a `typedef` for the operating system dependent encoded
 character type used to represent pathnames.
 The value of the `preferred_separator` member is the operating system
-dependent *preferred-separator* character ([[fs.path.generic]]).
-[*Example 1*: For POSIX-based operating systems, `value_type` is `char`
 and `preferred_separator` is the slash character (`'/'`). For
 Windows-based operating systems, `value_type` is `wchar_t` and
 `preferred_separator` is the backslash character
 (`L'\\'`). — *end example*]
@@ -6744,31 +7638,42 @@ preferred-separator:
 ``` bnf
 fallback-separator:
     /, if *preferred-separator* is not /
 ```
-[*Note 1*: Operating systems often place restrictions on the characters
-that may be used in a *filename*. For wide portability, users may wish
-to limit *filename* characters to the POSIX Portable Filename Character
-Set:
   `A B C D E F G H I J K L M N O P Q R S T U V W X Y Z`
   `a b c d e f g h i j k l m n o p q r s t u v w x y z`
   `0 1 2 3 4 5 6 7 8 9 . _ -` — *end note*]
 Except in a *root-name*, multiple successive *directory-separator*
 characters are considered to be the same as one *directory-separator*
 character.
-The filename *dot* ([[fs.def.filename]]) is treated as a reference to
-the current directory. The filename *dot-dot* ([[fs.def.filename]]) is
-treated as a reference to the parent directory. What the filename
-*dot-dot* refers to relative to *root-directory* is
 *implementation-defined*. Specific filenames may have special meanings
 for a particular operating system.
-A *root-name* identifies the starting location for pathname resolution (
-[[fs.def.pathres]]). If there are no operating system dependent
 *root-name*s, at least one *implementation-defined* *root-name* is
 required.
 [*Note 2*: Many operating systems define a name beginning with two
 *directory-separator* characters as a *root-name* that identifies
@@ -6781,17 +7686,42 @@ longest sequence of characters is chosen.
 [*Note 3*: On a POSIX-like operating system, it is impossible to have a
 *root-name* and a *relative-path* without an intervening
 *root-directory* element. — *end note*]
-#### `path` conversions <a id="fs.path.cvt">[[fs.path.cvt]]</a>
-##### `path` argument format conversions <a id="fs.path.fmt.cvt">[[fs.path.fmt.cvt]]</a>
 [*Note 1*:
-The format conversions described in this section are not applied on
 POSIX-based operating systems because on these systems:
 - The generic format is acceptable as a native path.
 - There is no need to distinguish between native format and generic
   format in function arguments.
@@ -6800,15 +7730,15 @@ POSIX-based operating systems because on these systems:
 — *end note*]
 Several functions are defined to accept *detected-format* arguments,
 which are character sequences. A detected-format argument represents a
-path using either a pathname in the generic format (
-[[fs.path.generic]]) or a pathname in the native format (
-[[fs.def.native]]). Such an argument is taken to be in the generic
-format if and only if it matches the generic format and is not
-acceptable to the operating system as a native path.
 [*Note 2*: Some operating systems may have no unambiguous way to
 distinguish between native format and generic format arguments. This is
 by design as it simplifies use for operating systems that do not require
 disambiguation. An implementation for an operating system where
@@ -6827,12 +7757,12 @@ native-to-generic and generic-to-native formats respectively. If
 If the native format requires paths for regular files to be formatted
 differently from paths for directories, the path shall be treated as a
 directory path if its last element is a *directory-separator*, otherwise
 it shall be treated as a path to a regular file.
-[*Note 4*: A path stores a native format pathname (
-[[fs.path.native.obs]]) and acts as if it also stores a generic format
 pathname, related as given below. The implementation may generate the
 generic format pathname based on the native format pathname (and
 possibly other information) when requested. — *end note*]
 When a path is constructed from or is assigned a single representation
@@ -6845,95 +7775,101 @@ the other representation. The value *q* converts to *p* (by *G* or *N*
 as appropriate) if any such value does so; *q* is otherwise unspecified.
 [*Note 5*: If *q* is the result of converting any path at all, it is
 the result of converting *p*. — *end note*]
-##### `path` type and encoding conversions <a id="fs.path.type.cvt">[[fs.path.type.cvt]]</a>
 For member function arguments that take character sequences representing
 paths and for member functions returning strings, value type and
 encoding conversion is performed if the value type of the argument or
 return value differs from `path::value_type`. For the argument or return
 value, the method of conversion and the encoding to be converted to is
 determined by its value type:
-- `char`: The encoding is the native narrow encoding (
- [[fs.def.native.encode]]). The method of conversion, if any, is
-  operating system dependent. \[*Note 6*: For POSIX-based operating
- systems `path::value_type` is `char` so no conversion from `char`
- value type arguments or to `char` value type return values is
- performed. For Windows-based operating systems, the native narrow
-  encoding is determined by calling a Windows API
   function. — *end note*] \[*Note 7*: This results in behavior
   identical to other C and C++ standard library functions that perform
-  file operations using narrow character strings to identify paths.
   Changing this behavior would be surprising and error
   prone. — *end note*]
-- `wchar_t`: The encoding is the native wide encoding (
- [[fs.def.native.encode]]). The method of conversion is unspecified.
- \[*Note 8*: For Windows-based operating systems `path::value_type` is
-  `wchar_t` so no conversion from `wchar_t` value type arguments or to
- `wchar_t` value type return values is performed. — *end note*]
 - `char16_t`: The encoding is UTF-16. The method of conversion is
   unspecified.
 - `char32_t`: The encoding is UTF-32. The method of conversion is
   unspecified.
 If the encoding being converted to has no representation for source
 characters, the resulting converted characters, if any, are unspecified.
 Implementations should not modify member function arguments if already
 of type `path::value_type`.
-#### `path` requirements <a id="fs.path.req">[[fs.path.req]]</a>
-In addition to the requirements ([[fs.req]]), function template
-parameters named `Source` shall be one of:
 - `basic_string<EcharT, traits, Allocator>`. A function argument
   `const Source&` `source` shall have an effective range
   \[`source.begin()`, `source.end()`).
 - `basic_string_view<EcharT, traits>`. A function argument
   `const Source&` `source` shall have an effective range
   \[`source.begin()`, `source.end()`).
-- A type meeting the input iterator requirements that iterates over a
-  NTCTS. The value type shall be an encoded character type. A function
-  argument `const Source&` `source` shall have an effective range
-  \[`source`, `end`) where `end` is the first iterator value with an
-  element value equal to `iterator_traits<Source>::value_type()`.
 - A character array that after array-to-pointer decay results in a
   pointer to the start of a NTCTS. The value type shall be an encoded
   character type. A function argument `const Source&` `source` shall
   have an effective range \[`source`, `end`) where `end` is the first
   iterator value with an element value equal to
   `iterator_traits<decay_t<Source>>::value_type()`.
 Functions taking template parameters named `Source` shall not
-participate in overload resolution unless either
 - `Source` is a specialization of `basic_string` or `basic_string_view`,
   or
 - the *qualified-id* `iterator_traits<decay_t<Source>>::value_type` is
-  valid and denotes a possibly `const` encoded character type (
-  [[temp.deduct]]).
-[*Note 1*: See path conversions ([[fs.path.cvt]]) for how the value
-types above and their encodings convert to `path::value_type` and its
 encoding. — *end note*]
 Arguments of type `Source` shall not be null pointers.
-#### `path` members <a id="fs.path.member">[[fs.path.member]]</a>
-##### `path` constructors <a id="fs.path.construct">[[fs.path.construct]]</a>
 ``` cpp
 path() noexcept;
 ```
-*Effects:* Constructs an object of class `path`.
-*Postconditions:* `empty() == true`.
 ``` cpp
 path(const path& p);
 path(path&& p) noexcept;
 ```
@@ -6946,49 +7882,48 @@ state.
 ``` cpp
 path(string_type&& source, format fmt = auto_format);
 ```
 *Effects:* Constructs an object of class `path` for which the pathname
-in the detected-format of `source` has the original value of
-`source` ([[fs.path.fmt.cvt]]), converting format if
-required ([[fs.path.fmt.cvt]]). `source` is left in a valid but
-unspecified state.
 ``` cpp
 template<class Source>
   path(const Source& source, format fmt = auto_format);
 template<class InputIterator>
   path(InputIterator first, InputIterator last, format fmt = auto_format);
 ```
-*Effects:* Let `s` be the effective range of `source` ([[fs.path.req]])
-or the range \[`first`, `last`), with the encoding converted if
-required ([[fs.path.cvt]]). Finds the detected-format of
-`s` ([[fs.path.fmt.cvt]]) and constructs an object of class `path` for
-which the pathname in that format is `s`.
 ``` cpp
 template<class Source>
   path(const Source& source, const locale& loc, format fmt = auto_format);
 template<class InputIterator>
   path(InputIterator first, InputIterator last, const locale& loc, format fmt = auto_format);
 ```
-*Requires:* The value type of `Source` and `InputIterator` is `char`.
 *Effects:* Let `s` be the effective range of `source` or the range
 \[`first`, `last`), after converting the encoding as follows:
 - If `value_type` is `wchar_t`, converts to the native wide
-  encoding ([[fs.def.native.encode]]) using the
   `codecvt<wchar_t, char, mbstate_t>` facet of `loc`.
 - Otherwise a conversion is performed using the
   `codecvt<wchar_t, char, mbstate_t>` facet of `loc`, and then a second
-  conversion to the current narrow encoding.
-Finds the detected-format of `s` ([[fs.path.fmt.cvt]]) and constructs
-an object of class `path` for which the pathname in that format is `s`.
 [*Example 1*:
 A string is to be read from a database that is encoded in ISO/IEC
 8859-1, and used to create a directory:
@@ -7002,27 +7937,27 @@ fs::create_directory(fs::path(latin1_string, latin1_locale));
 ```
 For POSIX-based operating systems, the path is constructed by first
 using `latin1_facet` to convert ISO/IEC 8859-1 encoded `latin1_string`
 to a wide character string in the native wide
-encoding ([[fs.def.native.encode]]). The resulting wide string is then
-converted to a narrow character pathname string in the current native
-narrow encoding. If the native wide encoding is UTF-16 or UTF-32, and
-the current native narrow encoding is UTF-8, all of the characters in
 the ISO/IEC 8859-1 character set will be converted to their Unicode
-representation, but for other native narrow encodings some characters
 may have no representation.
 For Windows-based operating systems, the path is constructed by using
 `latin1_facet` to convert ISO/IEC 8859-1 encoded `latin1_string` to a
 UTF-16 encoded wide character pathname string. All of the characters in
 the ISO/IEC 8859-1 character set will be converted to their Unicode
 representation.
 — *end example*]
-##### `path` assignments <a id="fs.path.assign">[[fs.path.assign]]</a>
 ``` cpp
 path& operator=(const path& p);
 ```
@@ -7062,18 +7997,18 @@ template <class Source>
   path& assign(const Source& source);
 template<class InputIterator>
   path& assign(InputIterator first, InputIterator last);
 ```
-*Effects:* Let `s` be the effective range of `source` ([[fs.path.req]])
-or the range \[`first`, `last`), with the encoding converted if
-required ([[fs.path.cvt]]). Finds the detected-format of
-`s` ([[fs.path.fmt.cvt]]) and sets the pathname in that format to `s`.
 *Returns:* `*this`.
-##### `path` appends <a id="fs.path.append">[[fs.path.append]]</a>
 The append operations use `operator/=` to denote their semantic effect
 of appending *preferred-separator* when needed.
 ``` cpp
@@ -7096,26 +8031,28 @@ Otherwise, modifies `*this` as if by these steps:
   pathname.
 [*Example 2*:
 Even if `//host` is interpreted as a *root-name*, both of the paths
-`path("//host")/"foo"` and `path("//host/")/"foo"` equal `"//host/foo"`.
 Expression examples:
 ``` cpp
 // On POSIX,
-path("foo") / ""; // yields "foo/"
-path("foo") / "/bar"; // yields "/bar"
-// On Windows, backslashes replace slashes in the above yields
 // On Windows,
-path("foo") / "c:/bar"; // yields "c:/bar"
-path("foo") / "c:"; // yields "c:"
-path("c:") / ""; // yields "c:"
-path("c:foo") / "/bar"; // yields "c:/bar"
-path("c:foo") / "c:bar"; // yields "c:foo/bar"
 ```
 — *end example*]
 *Returns:* `*this`.
@@ -7134,22 +8071,19 @@ template <class InputIterator>
   path& append(InputIterator first, InputIterator last);
 ```
 *Effects:* Equivalent to: `return operator/=(path(first, last));`
-##### `path` concatenation <a id="fs.path.concat">[[fs.path.concat]]</a>
 ``` cpp
 path& operator+=(const path& x);
 path& operator+=(const string_type& x);
 path& operator+=(basic_string_view<value_type> x);
 path& operator+=(const value_type* x);
-path& operator+=(value_type x);
 template<class Source>
   path& operator+=(const Source& x);
-template <class EcharT>
-  path& operator+=(EcharT x);
 template<class Source>
   path& concat(const Source& x);
 ```
 *Effects:* Appends `path(x).native()` to the pathname in the native
@@ -7158,24 +8092,32 @@ format.
 [*Note 2*: This directly manipulates the value of `native()` and may
 not be portable between operating systems. — *end note*]
 *Returns:* `*this`.
 ``` cpp
 template<class InputIterator>
   path& concat(InputIterator first, InputIterator last);
 ```
-*Effects:* Equivalent to `return *this += path(first, last)`.
-##### `path` modifiers <a id="fs.path.modifiers">[[fs.path.modifiers]]</a>
 ``` cpp
 void clear() noexcept;
 ```
-*Postconditions:* `empty() == true`.
 ``` cpp
 path& make_preferred();
 ```
@@ -7213,15 +8155,15 @@ output is:
 ``` cpp
 path& remove_filename();
 ```
-*Postconditions:* `!has_filename()`.
 *Effects:* Remove the generic format pathname of `filename()` from the
 generic format pathname.
 *Returns:* `*this`.
 [*Example 4*:
 ``` cpp
@@ -7259,12 +8201,12 @@ path("/").replace_filename("bar");     // yields "/bar" on POSIX
 path& replace_extension(const path& replacement = path());
 ```
 *Effects:*
-- Any existing `extension()(` [[fs.path.decompose]]`)` is removed from
- the pathname in the generic format, then
 - If `replacement` is not empty and does not begin with a dot character,
   a dot character is appended to the pathname in the generic format,
   then
 - `operator+=(replacement);`.
@@ -7276,14 +8218,14 @@ void swap(path& rhs) noexcept;
 *Effects:* Swaps the contents (in all formats) of the two paths.
 *Complexity:* Constant time.
-##### `path` native format observers <a id="fs.path.native.obs">[[fs.path.native.obs]]</a>
 The string returned by all native format observers is in the native
-pathname format ([[fs.def.native]]).
 ``` cpp
 const string_type& native() const noexcept;
 ```
@@ -7291,11 +8233,11 @@ const string_type& native() const noexcept;
 ``` cpp
 const value_type* c_str() const noexcept;
 ```
-*Returns:* Equivalent to `native().c_str()`.
 ``` cpp
 operator string_type() const;
 ```
@@ -7319,26 +8261,25 @@ be performed by `a`. Conversion, if any, is specified by
 [[fs.path.cvt]].
 ``` cpp
 std::string string() const;
 std::wstring wstring() const;
-std::string u8string() const;
 std::u16string u16string() const;
 std::u32string u32string() const;
 ```
-*Returns:* `pathstring`.
 *Remarks:* Conversion, if any, is performed as specified by
-[[fs.path.cvt]]. The encoding of the string returned by `u8string()` is
-always UTF-8.
-##### `path` generic format observers <a id="fs.path.generic.obs">[[fs.path.generic.obs]]</a>
 Generic format observer functions return strings formatted according to
-the generic pathname format ([[fs.path.generic]]). A single slash
-(`'/'`) character is used as the *directory-separator*.
 [*Example 1*:
 On an operating system that uses backslash as its *preferred-separator*,
@@ -7364,53 +8305,51 @@ be performed by `a`. Conversion, if any, is specified by
 [[fs.path.cvt]].
 ``` cpp
 std::string generic_string() const;
 std::wstring generic_wstring() const;
-std::string generic_u8string() const;
 std::u16string generic_u16string() const;
 std::u32string generic_u32string() const;
 ```
 *Returns:* The pathname in the generic format.
-*Remarks:* Conversion, if any, is specified by  [[fs.path.cvt]]. The
-encoding of the string returned by `generic_u8string()` is always UTF-8.
-##### `path` compare <a id="fs.path.compare">[[fs.path.compare]]</a>
 ``` cpp
 int compare(const path& p) const noexcept;
 ```
 *Returns:*
-- A value less than `0`, if `native()` for the elements of `*this` are
- lexicographically less than `native()` for the elements of `p`;
- otherwise,
-- a value greater than `0`, if `native()` for the elements of `*this`
- are lexicographically greater than `native()` for the elements of `p`;
-  otherwise,
-- `0`.
-*Remarks:* The elements are determined as if by iteration over the
-half-open range \[`begin()`, `end()`) for `*this` and `p`.
 ``` cpp
-int compare(const string_type& s) const
 int compare(basic_string_view<value_type> s) const;
 ```
-*Returns:* `compare(path(s))`.
-``` cpp
-int compare(const value_type* s) const
-```
-*Returns:* `compare(path(s))`.
-##### `path` decomposition <a id="fs.path.decompose">[[fs.path.decompose]]</a>
 ``` cpp
 path root_name() const;
 ```
@@ -7433,20 +8372,21 @@ path root_path() const;
 ``` cpp
 path relative_path() const;
 ```
 *Returns:* A `path` composed from the pathname in the generic format, if
-`!empty()`, beginning with the first *filename* after *root-path*.
-Otherwise, `path()`.
 ``` cpp
 path parent_path() const;
 ```
-*Returns:* `*this` if `!has_relative_path()`, otherwise a path whose
-generic format pathname is the longest prefix of the generic format
-pathname of `*this` that produces one fewer element in its iteration.
 ``` cpp
 path filename() const;
 ```
@@ -7493,11 +8433,11 @@ for (; !p.extension().empty(); p = p.stem())
 ``` cpp
 path extension() const;
 ```
-*Returns:* a path whose pathname in the generic format is the suffix of
 `filename()` not included in `stem()`.
 [*Example 8*:
 ``` cpp
@@ -7516,18 +8456,18 @@ extension. — *end note*]
 [*Note 5*: On non-POSIX operating systems, for a path `p`, it may not
 be the case that `p.stem() + p.extension() == p.filename()`, even though
 the generic format pathnames are the same. — *end note*]
-##### `path` query <a id="fs.path.query">[[fs.path.query]]</a>
 ``` cpp
-bool empty() const noexcept;
 ```
-*Returns:* `true` if the pathname in the generic format is empty, else
-`false`.
 ``` cpp
 bool has_root_path() const;
 ```
@@ -7578,11 +8518,11 @@ bool has_extension() const;
 ``` cpp
 bool is_absolute() const;
 ```
 *Returns:* `true` if the pathname in the native format contains an
-absolute path ([[fs.def.absolute.path]]), else `false`.
 [*Example 9*: `path("/").is_absolute()` is `true` for POSIX-based
 operating systems, and `false` for Windows-based operating
 systems. — *end example*]
@@ -7590,18 +8530,18 @@ systems. — *end example*]
 bool is_relative() const;
 ```
 *Returns:* `!is_absolute()`.
-##### `path` generation <a id="fs.path.gen">[[fs.path.gen]]</a>
 ``` cpp
 path lexically_normal() const;
 ```
 *Returns:* A path whose pathname in the generic format is the normal
-form ([[fs.def.normal.form]]) of the pathname in the generic format of
 `*this`.
 [*Example 10*:
 ``` cpp
@@ -7618,29 +8558,40 @@ slashes, but that does not affect `path` equality.
 ``` cpp
 path lexically_relative(const path& base) const;
 ```
 *Returns:* `*this` made relative to `base`. Does not
-resolve ([[fs.def.pathres]]) symlinks. Does not first
-normalize ([[fs.def.normal.form]]) `*this` or `base`.
-*Effects:* If `root_name() != base.root_name()` is `true` or
-`is_absolute() != base.is_absolute()` is `true` or
-`!has_root_directory() && base.has_root_directory()` is `true`, returns
-`path()`. Determines the first mismatched element of `*this` and `base`
-as if by:
 ``` cpp
 auto [a, b] = mismatch(begin(), end(), base.begin(), base.end());
 ```
 Then,
 - if `a == end()` and `b == base.end()`, returns `path(".")`; otherwise
 - let `n` be the number of *filename* elements in \[`b`, `base.end()`)
-  that are not *dot* or *dot-dot* minus the number that are *dot-dot*.
-  If `n<0,` returns `path()`; otherwise
 - returns an object of class `path` that is default-constructed,
   followed by
   - application of `operator/=(path(".."))` `n` times, and then
   - application of `operator/=` for each element in \[`a`, `end()`).
@@ -7659,41 +8610,41 @@ The above assertions will succeed. On Windows, the returned path’s
 *directory-separator* characters will be backslashes rather than
 slashes, but that does not affect `path` equality.
 — *end example*]
-[*Note 6*: If symlink following semantics are desired, use the
 operational function `relative()`. — *end note*]
-[*Note 7*: If normalization ([[fs.def.normal.form]]) is needed to
-ensure consistent matching of elements, apply `lexically_normal()` to
-`*this`, `base`, or both. — *end note*]
 ``` cpp
 path lexically_proximate(const path& base) const;
 ```
 *Returns:* If the value of `lexically_relative(base)` is not an empty
 path, return it. Otherwise return `*this`.
-[*Note 8*: If symlink following semantics are desired, use the
 operational function `proximate()`. — *end note*]
-[*Note 9*: If normalization ([[fs.def.normal.form]]) is needed to
-ensure consistent matching of elements, apply `lexically_normal()` to
-`*this`, `base`, or both. — *end note*]
-#### `path` iterators <a id="fs.path.itr">[[fs.path.itr]]</a>
 Path iterators iterate over the elements of the pathname in the generic
-format ([[fs.path.generic]]).
-A `path::iterator` is a constant iterator satisfying all the
-requirements of a bidirectional iterator ([[bidirectional.iterators]])
-except that, for dereferenceable iterators `a` and `b` of type
-`path::iterator` with `a == b`, there is no requirement that `*a` and
-`*b` are bound to the same object. Its `value_type` is `path`.
 Calling any non-const member function of a `path` object invalidates all
 iterators referring to elements of that object.
 For the elements of the pathname in the generic format, the forward
@@ -7720,171 +8671,94 @@ list above. If no elements are present, the end iterator.
 iterator end() const;
 ```
 *Returns:* The end iterator.
-#### `path` non-member functions <a id="fs.path.nonmember">[[fs.path.nonmember]]</a>
 ``` cpp
 void swap(path& lhs, path& rhs) noexcept;
 ```
-*Effects:* Equivalent to: `lhs.swap(rhs);`
 ``` cpp
 size_t hash_value (const path& p) noexcept;
 ```
 *Returns:* A hash value for the path `p`. If for two paths, `p1 == p2`
 then `hash_value(p1) == hash_value(p2)`.
 ``` cpp
-bool operator< (const path& lhs, const path& rhs) noexcept;
 ```
-*Returns:* `lhs.compare(rhs) < 0`.
-``` cpp
-bool operator<=(const path& lhs, const path& rhs) noexcept;
-```
-*Returns:* `!(rhs < lhs)`.
-``` cpp
-bool operator> (const path& lhs, const path& rhs) noexcept;
-```
-*Returns:* `rhs < lhs`.
-``` cpp
-bool operator>=(const path& lhs, const path& rhs) noexcept;
-```
-*Returns:* `!(lhs < rhs)`.
-``` cpp
-bool operator==(const path& lhs, const path& rhs) noexcept;
-```
-*Returns:* `!(lhs < rhs) && !(rhs < lhs)`.
 [*Note 1*:
 Path equality and path equivalence have different semantics.
 - Equality is determined by the `path` non-member `operator==`, which
-  considers the two path’s lexical representations only.
   \[*Example 1*: `path("foo") == "bar"` is never
   `true`. — *end example*]
 - Equivalence is determined by the `equivalent()` non-member function,
-  which determines if two paths resolve ([[fs.def.pathres]]) to the
- same file system entity. \[*Example 2*: `equivalent("foo", "bar")`
- will be `true` when both paths resolve to the same
-  file. — *end example*]
 Programmers wishing to determine if two paths are “the same” must decide
 if “the same” means “the same representation” or “resolve to the same
 actual file”, and choose the appropriate function accordingly.
 — *end note*]
 ``` cpp
-bool operator!=(const path& lhs, const path& rhs) noexcept;
 ```
-*Returns:* `!(lhs == rhs)`.
 ``` cpp
-path operator/ (const path& lhs, const path& rhs);
 ```
 *Effects:* Equivalent to: `return path(lhs) /= rhs;`
-##### `path` inserter and extractor <a id="fs.path.io">[[fs.path.io]]</a>
-``` cpp
-template <class charT, class traits>
-  basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os, const path& p);
-```
-*Effects:* Equivalent to: `os << quoted(p.string<charT, traits>());`
-[*Note 2*: The `quoted` function is described
-in  [[quoted.manip]]. — *end note*]
-*Returns:* `os`.
-``` cpp
-template <class charT, class traits>
-  basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is, path& p);
-```
-*Effects:* Equivalent to:
-``` cpp
-basic_string<charT, traits> tmp;
-is >> quoted(tmp);
-p = tmp;
-```
-*Returns:* `is`.
-##### `path` factory functions <a id="fs.path.factory">[[fs.path.factory]]</a>
-``` cpp
-template <class Source>
-  path u8path(const Source& source);
-template <class InputIterator>
-  path u8path(InputIterator first, InputIterator last);
-```
-*Requires:* The `source` and \[`first`, `last`) sequences are UTF-8
-encoded. The value type of `Source` and `InputIterator` is `char`.
-*Returns:*
-- If `value_type` is `char` and the current native narrow
-  encoding ([[fs.def.native.encode]]) is UTF-8, return `path(source)`
-  or `path(first, last)`; otherwise,
-- if `value_type` is `wchar_t` and the native wide encoding is UTF-16,
-  or if `value_type` is `char16_t` or `char32_t`, convert `source` or
-  \[`first`, `last`) to a temporary, `tmp`, of type `string_type` and
-  return `path(tmp)`; otherwise,
-- convert `source` or \[`first`, `last`) to a temporary, `tmp`, of type
-  `u32string` and return `path(tmp)`.
-*Remarks:* Argument format conversion ([[fs.path.fmt.cvt]]) applies to
-the arguments for these functions. How Unicode encoding conversions are
-performed is unspecified.
-[*Example 1*:
-A string is to be read from a database that is encoded in UTF-8, and
-used to create a directory using the native encoding for filenames:
-``` cpp
-namespace fs = std::filesystem;
-std::string utf8_string = read_utf8_data();
-fs::create_directory(fs::u8path(utf8_string));
-```
-For POSIX-based operating systems with the native narrow encoding set to
-UTF-8, no encoding or type conversion occurs.
-For POSIX-based operating systems with the native narrow encoding not
-set to UTF-8, a conversion to UTF-32 occurs, followed by a conversion to
-the current native narrow encoding. Some Unicode characters may have no
-native character set representation.
-For Windows-based operating systems a conversion from UTF-8 to UTF-16
-occurs.
-— *end example*]
-### Class `filesystem_error` <a id="fs.class.filesystem_error">[[fs.class.filesystem_error]]</a>
 ``` cpp
 namespace std::filesystem {
   class filesystem_error : public system_error {
   public:
@@ -7900,65 +8774,50 @@ namespace std::filesystem {
   };
 }
 ```
 The class `filesystem_error` defines the type of objects thrown as
-exceptions to report file system errors from functions described in this
-subclause.
-#### `filesystem_error` members <a id="filesystem_error.members">[[filesystem_error.members]]</a>
 Constructors are provided that store zero, one, or two paths associated
 with an error.
 ``` cpp
 filesystem_error(const string& what_arg, error_code ec);
 ```
-*Postconditions:* The postconditions of this function are indicated in
-Table  [[tab:filesystem_error.1]].
-**Table: `filesystem_error(const string&, error_code)` effects** <a id="tab:filesystem_error.1">[tab:filesystem_error.1]</a>
-| Expression              | Value              |
-| ----------------------- | ------------------ |
-| `runtime_error::what()` | `what_arg.c_str()` |
-| `code()`                | `ec`               |
-| `path1().empty()`       | `true`             |
-| `path2().empty()`       | `true`             |
 ``` cpp
 filesystem_error(const string& what_arg, const path& p1, error_code ec);
 ```
-*Postconditions:* The postconditions of this function are indicated in
-Table  [[tab:filesystem_error.2]].
-**Table: `filesystem_error(const string&, const path&, error_code)` effects** <a id="tab:filesystem_error.2">[tab:filesystem_error.2]</a>
-| Expression              | Value                            |
-| ----------------------- | -------------------------------- |
-| `runtime_error::what()` | `what_arg.c_str()`               |
-| `code()`                | `ec`                             |
-| `path1()`               | Reference to stored copy of `p1` |
-| `path2().empty()`       | `true`                           |
 ``` cpp
 filesystem_error(const string& what_arg, const path& p1, const path& p2, error_code ec);
 ```
-*Postconditions:* The postconditions of this function are indicated in
-Table  [[tab:filesystem_error.3]].
-**Table: `filesystem_error(const string&, const path&, const path&, error_code)` effects** <a id="tab:filesystem_error.3">[tab:filesystem_error.3]</a>
-| Expression              | Value                            |
-| ----------------------- | -------------------------------- |
-| `runtime_error::what()` | `what_arg.c_str()`               |
-| `code()`                | `ec`                             |
-| `path1()`               | Reference to stored copy of `p1` |
-| `path2()`               | Reference to stored copy of `p2` |
 ``` cpp
 const path& path1() const noexcept;
 ```
@@ -7974,45 +8833,46 @@ or, if none, an empty path.
 ``` cpp
 const char* what() const noexcept override;
 ```
-*Returns:* A string containing `runtime_error::what()`. The exact format
-is unspecified. Implementations are encouraged but not required to
-include `path1.native_string()` if not empty, `path2.native_string()` if
-not empty, and `system_error::what()` strings in the returned string.
 ### Enumerations <a id="fs.enum">[[fs.enum]]</a>
 #### Enum `path::format` <a id="fs.enum.path.format">[[fs.enum.path.format]]</a>
 This enum specifies constants used to identify the format of the
-character sequence, with the meanings listed in Table
-[[tab:enum.path.format]].
 [*Note 1*: For POSIX-based systems, native and generic formats are
 equivalent and the character sequence should always be interpreted in
 the same way. — *end note*]
-#### Enum class `file_type` <a id="fs.enum.file_type">[[fs.enum.file_type]]</a>
 This enum class specifies constants used to identify file types, with
-the meanings listed in Table  [[tab:fs.enum.file_type]].
 [*Note 1*: The file not being found is not considered an error while
 determining the type of a file. — *end note*]
 #### Enum class `copy_options` <a id="fs.enum.copy.opts">[[fs.enum.copy.opts]]</a>
-The `enum class` type `copy_options` is a bitmask type (
-[[bitmask.types]]) that specifies bitmask constants used to control the
-semantics of copy operations. The constants are specified in option
-groups with the meanings listed in Table  [[tab:fs.enum.copy_options]].
-Constant `none` is shown in each option group for purposes of
 exposition; implementations shall provide only a single definition.
-**Table: Enum class `copy_options`** <a id="tab:fs.enum.copy_options">[tab:fs.enum.copy_options]</a>
 | Constant             | Meaning                                                                                                                                               |
 | -------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `none`               | (Default) Error; file already exists.                                                                                                                 |
 | `skip_existing`      | Do not overwrite existing file, do not report an error.                                                                                               |
@@ -8026,15 +8886,15 @@ exposition; implementations shall provide only a single definition.
 | `create_hard_links`  | Make hard links instead of copies of files.                                                                                                           |
 #### Enum class `perms` <a id="fs.enum.perms">[[fs.enum.perms]]</a>
-The `enum class` type `perms` is a bitmask type ([[bitmask.types]])
-that specifies bitmask constants used to identify file permissions, with
-the meanings listed in Table  [[tab:fs.enum.perms]].
-**Table: Enum class `perms`** <a id="tab:fs.enum.perms">[tab:fs.enum.perms]</a>
 | Name           | Value (octal) | POSIX macro | Definition or notes                                                                                              |
 | -------------- | ------------- | ----------- | ---------------------------------------------------------------------------------------------------------------- |
 | `none`         | `0`           |             | There are no permissions set for the file.                                                                       |
 | `owner_read`   | `0400`        | `S_IRUSR`   | Read permission, owner                                                                                           |
@@ -8057,81 +8917,85 @@ the meanings listed in Table  [[tab:fs.enum.perms]].
 | `unknown`      | `0xFFFF`      |             | The permissions are not known, such as when a `file_status` object is created without specifying the permissions |
 #### Enum class `perm_options` <a id="fs.enum.perm.opts">[[fs.enum.perm.opts]]</a>
-The `enum class` type `perm_options` is a bitmask type (
-[[bitmask.types]]) that specifies bitmask constants used to control the
-semantics of permissions operations, with the meanings listed in Table
-[[tab:enum.perm_options]]. The bitmask constants are bitmask elements.
-In Table  [[tab:enum.perm_options]] `perm` denotes a value of type
-`perms` passed to `permissions`.
-**Table: Enum class `perm_options`** <a id="tab:enum.perm_options">[tab:enum.perm_options]</a>
 | Name       | Meaning                                                                                                                                                 |
-| ---------- | ----------------------------------------------------------------------------------------------------------------------------------------------- |
 | `replace`  | `permissions` shall replace the file's permission bits with `perm`                                                                                      |
-| `add`      | `permissions` shall replace the file's permission bits with the bitwise OR of `perm` and the file's current permission bits.                    |
-| `remove`   | `permissions` shall replace the file's permission bits with the bitwise AND of the complement of `perm` and the file's current permission bits. |
 | `nofollow` | `permissions` shall change the permissions of a symbolic link itself rather than the permissions of the file the link resolves to.                      |
 #### Enum class `directory_options` <a id="fs.enum.dir.opts">[[fs.enum.dir.opts]]</a>
-The `enum class` type `directory_options` is a bitmask type (
-[[bitmask.types]]) that specifies bitmask constants used to identify
-directory traversal options, with the meanings listed in Table
-[[tab:fs.enum.directory_options]].
-**Table: Enum class `directory_options`** <a id="tab:fs.enum.directory_options">[tab:fs.enum.directory_options]</a>
 | Name                       | Meaning                                                            |
 | -------------------------- | ------------------------------------------------------------------ |
 | `none`                     | (Default) Skip directory symlinks, permission denied is an error.  |
 | `follow_directory_symlink` | Follow rather than skip directory symlinks.                        |
 | `skip_permission_denied`   | Skip directories that would otherwise result in permission denied. |
-### Class `file_status` <a id="fs.class.file_status">[[fs.class.file_status]]</a>
 ``` cpp
 namespace std::filesystem {
   class file_status {
   public:
-    // [fs.file_status.cons], constructors and destructor
     file_status() noexcept : file_status(file_type::none) {}
     explicit file_status(file_type ft,
                          perms prms = perms::unknown) noexcept;
     file_status(const file_status&) noexcept = default;
     file_status(file_status&&) noexcept = default;
     ~file_status();
-    // assignments:
     file_status& operator=(const file_status&) noexcept = default;
     file_status& operator=(file_status&&) noexcept = default;
-    // [fs.file_status.mods], modifiers
     void       type(file_type ft) noexcept;
     void       permissions(perms prms) noexcept;
-    // [fs.file_status.obs], observers
     file_type  type() const noexcept;
     perms      permissions() const noexcept;
   };
 }
 ```
-#### `file_status` constructors <a id="fs.file_status.cons">[[fs.file_status.cons]]</a>
 ``` cpp
 explicit file_status(file_type ft, perms prms = perms::unknown) noexcept;
 ```
-*Postconditions:* `type() == ft` and `permissions() == prms`.
-#### `file_status` observers <a id="fs.file_status.obs">[[fs.file_status.obs]]</a>
 ``` cpp
 file_type type() const noexcept;
 ```
@@ -8145,53 +9009,53 @@ perms permissions() const noexcept;
 *Returns:* The value of `permissions()` specified by the postconditions
 of the most recent call to a constructor, `operator=`, or
 `permissions(perms)` function.
-#### `file_status` modifiers <a id="fs.file_status.mods">[[fs.file_status.mods]]</a>
 ``` cpp
 void type(file_type ft) noexcept;
 ```
-*Postconditions:* `type() == ft`.
 ``` cpp
 void permissions(perms prms) noexcept;
 ```
-*Postconditions:* `permissions() == prms`.
-### Class `directory_entry` <a id="fs.class.directory_entry">[[fs.class.directory_entry]]</a>
 ``` cpp
 namespace std::filesystem {
   class directory_entry {
   public:
     // [fs.dir.entry.cons], constructors and destructor
     directory_entry() noexcept = default;
     directory_entry(const directory_entry&) = default;
     directory_entry(directory_entry&&) noexcept = default;
-    explicit directory_entry(const path& p);
-    directory_entry(const path& p, error_code& ec);
     ~directory_entry();
-    // assignments:
     directory_entry& operator=(const directory_entry&) = default;
     directory_entry& operator=(directory_entry&&) noexcept = default;
     // [fs.dir.entry.mods], modifiers
-    void assign(const path& p);
-    void assign(const path& p, error_code& ec);
-    void replace_filename(const path& p);
-    void replace_filename(const path& p, error_code& ec);
     void refresh();
     void refresh(error_code& ec) noexcept;
     // [fs.dir.entry.obs], observers
-    const path& path() const noexcept;
-    operator const path&() const noexcept;
     bool exists() const;
     bool exists(error_code& ec) const noexcept;
     bool is_block_file() const;
     bool is_block_file(error_code& ec) const noexcept;
     bool is_character_file() const;
@@ -8217,36 +9081,32 @@ namespace std::filesystem {
     file_status status() const;
     file_status status(error_code& ec) const noexcept;
     file_status symlink_status() const;
     file_status symlink_status(error_code& ec) const noexcept;
-    bool operator< (const directory_entry& rhs) const noexcept;
     bool operator==(const directory_entry& rhs) const noexcept;
- bool operator!=(const directory_entry& rhs) const noexcept;
-    bool operator<=(const directory_entry& rhs) const noexcept;
-    bool operator> (const directory_entry& rhs) const noexcept;
-    bool operator>=(const directory_entry& rhs) const noexcept;
   private:
-    path pathobject; // exposition only
     friend class directory_iterator;    // exposition only
   };
 }
 ```
 A `directory_entry` object stores a `path` object and may store
 additional objects for file attributes such as hard link count, status,
 symlink status, file size, and last write time.
-Implementations are encouraged to store such additional file attributes
-during directory iteration if their values are available and storing the
-values would allow the implementation to eliminate file system accesses
-by `directory_entry` observer functions ([[fs.op.funcs]]). Such stored
-file attribute values are said to be *cached*.
-[*Note 1*: For purposes of exposition, class `directory_iterator` (
-[[fs.class.directory_iterator]]) is shown above as a friend of class
 `directory_entry`. Friendship allows the `directory_iterator`
 implementation to cache already available attribute values directly into
 a `directory_entry` object without the cost of an unneeded call to
 `refresh()`. — *end note*]
@@ -8278,41 +9138,40 @@ so will not result in a potentially expensive call to the
 `std::filesystem::last_write_time` function. The code is portable to any
 implementation, regardless of whether or not it employs caching.
 — *end example*]
-#### `directory_entry` constructors <a id="fs.dir.entry.cons">[[fs.dir.entry.cons]]</a>
 ``` cpp
-explicit directory_entry(const path& p);
-directory_entry(const path& p, error_code& ec);
 ```
-*Effects:* Constructs an object of type `directory_entry`, then
-`refresh()` or `refresh(ec)`, respectively.
-*Postconditions:* `path() == p` if no error occurs, otherwise
-`path() == std::filesystem::path()`.
 *Throws:* As specified in  [[fs.err.report]].
-#### `directory_entry` modifiers <a id="fs.dir.entry.mods">[[fs.dir.entry.mods]]</a>
 ``` cpp
-void assign(const path& p);
-void assign(const path& p, error_code& ec);
 ```
 *Effects:* Equivalent to `pathobject = p`, then `refresh()` or
 `refresh(ec)`, respectively. If an error occurs, the values of any
 cached attributes are unspecified.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
-void replace_filename(const path& p);
-void replace_filename(const path& p, error_code& ec);
 ```
 *Effects:* Equivalent to `pathobject.replace_filename(p)`, then
 `refresh()` or `refresh(ec)`, respectively. If an error occurs, the
 values of any cached attributes are unspecified.
@@ -8324,121 +9183,121 @@ void refresh();
 void refresh(error_code& ec) noexcept;
 ```
 *Effects:* Stores the current values of any cached attributes of the
 file `p` resolves to. If an error occurs, an error is
-reported ([[fs.err.report]]) and the values of any cached attributes
-are unspecified.
 *Throws:* As specified in  [[fs.err.report]].
-[*Note 1*: Implementations of
-`directory_iterator` ([[fs.class.directory_iterator]]) are prohibited
-from directly or indirectly calling the `refresh` function since it must
-access the external file system, and the objective of caching is to
-avoid unnecessary file system accesses. — *end note*]
-#### `directory_entry` observers <a id="fs.dir.entry.obs">[[fs.dir.entry.obs]]</a>
 Unqualified function names in the *Returns:* elements of the
 `directory_entry` observers described below refer to members of the
 `std::filesystem` namespace.
 ``` cpp
-const path& path() const noexcept;
-operator const path&() const noexcept;
 ```
 *Returns:* `pathobject`.
 ``` cpp
 bool exists() const;
 bool exists(error_code& ec) const noexcept;
 ```
-*Returns:* `exists(this->status())` or `exists(this->status(), ec)`,
 respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_block_file() const;
 bool is_block_file(error_code& ec) const noexcept;
 ```
 *Returns:* `is_block_file(this->status())` or
-`is_block_file(this->status(), ec)`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_character_file() const;
 bool is_character_file(error_code& ec) const noexcept;
 ```
 *Returns:* `is_character_file(this->status())` or
-`is_character_file(this->status(), ec)`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_directory() const;
 bool is_directory(error_code& ec) const noexcept;
 ```
 *Returns:* `is_directory(this->status())` or
-`is_directory(this->status(), ec)`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_fifo() const;
 bool is_fifo(error_code& ec) const noexcept;
 ```
-*Returns:* `is_fifo(this->status())` or `is_fifo(this->status(), ec)`,
 respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_other() const;
 bool is_other(error_code& ec) const noexcept;
 ```
-*Returns:* `is_other(this->status())` or `is_other(this->status(), ec)`,
 respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_regular_file() const;
 bool is_regular_file(error_code& ec) const noexcept;
 ```
 *Returns:* `is_regular_file(this->status())` or
-`is_regular_file(this->status(), ec)`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_socket() const;
 bool is_socket(error_code& ec) const noexcept;
 ```
-*Returns:* `is_socket(this->status())` or
-`is_socket(this->status(), ec)`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_symlink() const;
 bool is_symlink(error_code& ec) const noexcept;
 ```
 *Returns:* `is_symlink(this->symlink_status())` or
-`is_symlink(this->symlink_status(), ec)`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 uintmax_t file_size() const;
@@ -8497,49 +9356,24 @@ bool operator==(const directory_entry& rhs) const noexcept;
 ```
 *Returns:* `pathobject == rhs.pathobject`.
 ``` cpp
-bool operator!=(const directory_entry& rhs) const noexcept;
 ```
-*Returns:* `pathobject != rhs.pathobject`.
-``` cpp
-bool operator< (const directory_entry& rhs) const noexcept;
-```
-*Returns:* `pathobject < rhs.pathobject`.
-``` cpp
-bool operator<=(const directory_entry& rhs) const noexcept;
-```
-*Returns:* `pathobject <= rhs.pathobject`.
-``` cpp
-bool operator> (const directory_entry& rhs) const noexcept;
-```
-*Returns:* `pathobject > rhs.pathobject`.
-``` cpp
-bool operator>=(const directory_entry& rhs) const noexcept;
-```
-*Returns:* `pathobject >= rhs.pathobject`.
-### Class `directory_iterator` <a id="fs.class.directory_iterator">[[fs.class.directory_iterator]]</a>
 An object of type `directory_iterator` provides an iterator for a
 sequence of `directory_entry` elements representing the path and any
-cached attribute values ([[fs.class.directory_entry]]) for each file in
-a directory or in an *implementation-defined* directory-like file type.
 [*Note 1*: For iteration into sub-directories, see class
-`recursive_directory_iterator` (
-[[fs.class.rec.dir.itr]]). — *end note*]
 ``` cpp
 namespace std::filesystem {
   class directory_iterator {
   public:
@@ -8551,32 +9385,32 @@ namespace std::filesystem {
     // [fs.dir.itr.members], member functions
     directory_iterator() noexcept;
     explicit directory_iterator(const path& p);
     directory_iterator(const path& p, directory_options options);
-    directory_iterator(const path& p, error_code& ec) noexcept;
     directory_iterator(const path& p, directory_options options,
-                       error_code& ec) noexcept;
     directory_iterator(const directory_iterator& rhs);
     directory_iterator(directory_iterator&& rhs) noexcept;
     ~directory_iterator();
     directory_iterator& operator=(const directory_iterator& rhs);
     directory_iterator& operator=(directory_iterator&& rhs) noexcept;
     const directory_entry& operator*() const;
     const directory_entry* operator->() const;
     directory_iterator&    operator++();
-    directory_iterator&    increment(error_code& ec) noexcept;
     // other members as required by [input.iterators], input iterators
   };
 }
 ```
-`directory_iterator` satisfies the requirements of an input iterator (
-[[input.iterators]]).
 If an iterator of type `directory_iterator` reports an error or is
 advanced past the last directory element, that iterator shall become
 equal to the end iterator value. The `directory_iterator` default
 constructor shall create an iterator equal to the end iterator value,
@@ -8592,24 +9426,24 @@ object obtained by dereferencing a `directory_iterator` is a reference
 to a `path` object composed of the directory argument from which the
 iterator was constructed with filename of the directory entry appended
 as if by `operator/=`.
 Directory iteration shall not yield directory entries for the current
-(*dot*) and parent (*dot-dot*) directories.
 The order of directory entries obtained by dereferencing successive
 increments of a `directory_iterator` is unspecified.
 Constructors and non-const `directory_iterator` member functions store
-the values of any cached attributes ([[fs.class.directory_entry]]) in
-the `directory_entry` element returned by `operator*()`.
 `directory_iterator` member functions shall not directly or indirectly
 call any `directory_entry` `refresh` function.
 [*Note 2*: The exact mechanism for storing cached attribute values is
 not exposed to users. For exposition, class `directory_iterator` is
-shown in [[fs.class.directory_entry]] as a friend of class
 `directory_entry`. — *end note*]
 [*Note 3*: Programs performing directory iteration may wish to test if
 the path obtained by dereferencing a directory iterator actually exists.
 It could be a symbolic link to a non-existent file. Programs recursively
@@ -8620,23 +9454,23 @@ may wish to avoid following symbolic links. — *end note*]
 construction of a `directory_iterator` for the directory, it is
 unspecified whether or not subsequently incrementing the iterator will
 ever result in an iterator referencing the removed or added directory
 entry. See POSIX `readdir_r`. — *end note*]
-#### `directory_iterator` members <a id="fs.dir.itr.members">[[fs.dir.itr.members]]</a>
 ``` cpp
 directory_iterator() noexcept;
 ```
 *Effects:* Constructs the end iterator.
 ``` cpp
 explicit directory_iterator(const path& p);
 directory_iterator(const path& p, directory_options options);
-directory_iterator(const path& p, error_code& ec) noexcept;
-directory_iterator(const path& p, directory_options options, error_code& ec) noexcept;
 ```
 *Effects:* For the directory that `p` resolves to, constructs an
 iterator for the first element in a sequence of `directory_entry`
 elements representing the files in the directory, if any; otherwise the
@@ -8659,39 +9493,37 @@ error.
 ``` cpp
 directory_iterator(const directory_iterator& rhs);
 directory_iterator(directory_iterator&& rhs) noexcept;
 ```
-*Effects:* Constructs an object of class `directory_iterator`.
-*Postconditions:* `*this` has the original value of `rhs`.
 ``` cpp
 directory_iterator& operator=(const directory_iterator& rhs);
 directory_iterator& operator=(directory_iterator&& rhs) noexcept;
 ```
 *Effects:* If `*this` and `rhs` are the same object, the member has no
 effect.
-*Postconditions:* `*this` has the original value of `rhs`.
 *Returns:* `*this`.
 ``` cpp
 directory_iterator& operator++();
-directory_iterator& increment(error_code& ec) noexcept;
 ```
 *Effects:* As specified for the prefix increment operation of Input
-iterators ([[input.iterators]]).
 *Returns:* `*this`.
 *Throws:* As specified in  [[fs.err.report]].
-#### `directory_iterator` non-member functions <a id="fs.dir.itr.nonmembers">[[fs.dir.itr.nonmembers]]</a>
 These functions enable range access for `directory_iterator`.
 ``` cpp
 directory_iterator begin(directory_iterator iter) noexcept;
@@ -8725,12 +9557,12 @@ namespace std::filesystem {
     // [fs.rec.dir.itr.members], constructors and destructor
     recursive_directory_iterator() noexcept;
     explicit recursive_directory_iterator(const path& p);
     recursive_directory_iterator(const path& p, directory_options options);
     recursive_directory_iterator(const path& p, directory_options options,
-                                 error_code& ec) noexcept;
-    recursive_directory_iterator(const path& p, error_code& ec) noexcept;
     recursive_directory_iterator(const recursive_directory_iterator& rhs);
     recursive_directory_iterator(recursive_directory_iterator&& rhs) noexcept;
     ~recursive_directory_iterator();
     // [fs.rec.dir.itr.members], observers
@@ -8746,11 +9578,11 @@ namespace std::filesystem {
       operator=(const recursive_directory_iterator& rhs);
     recursive_directory_iterator&
       operator=(recursive_directory_iterator&& rhs) noexcept;
     recursive_directory_iterator& operator++();
-    recursive_directory_iterator& increment(error_code& ec) noexcept;
     void pop();
     void pop(error_code& ec);
     void disable_recursion_pending();
@@ -8767,38 +9599,38 @@ The behavior of a `recursive_directory_iterator` is the same as a
 `directory_iterator` unless otherwise specified.
 [*Note 1*: If the directory structure being iterated over contains
 cycles then the end iterator may be unreachable. — *end note*]
-#### `recursive_directory_iterator` members <a id="fs.rec.dir.itr.members">[[fs.rec.dir.itr.members]]</a>
 ``` cpp
 recursive_directory_iterator() noexcept;
 ```
 *Effects:* Constructs the end iterator.
 ``` cpp
 explicit recursive_directory_iterator(const path& p);
 recursive_directory_iterator(const path& p, directory_options options);
-recursive_directory_iterator(const path& p, directory_options options, error_code& ec) noexcept;
-recursive_directory_iterator(const path& p, error_code& ec) noexcept;
 ```
-*Effects:* Constructs a iterator representing the first entry in the
-directory `p` resolves to, if any; otherwise, the end iterator. However,
-if
 ``` cpp
 (options & directory_options::skip_permission_denied) != directory_options::none
 ```
 and construction encounters an error indicating that permission to
 access `p` is denied, constructs the end iterator and does not report an
 error.
-*Postconditions:* `options() == options` for the signatures with a
 `directory_options` argument, otherwise
 `options() == directory_options::none`.
 *Throws:* As specified in  [[fs.err.report]].
@@ -8806,42 +9638,38 @@ error.
 `recursive_directory_iterator(".")` rather than
 `recursive_directory_iterator("")`. — *end note*]
 [*Note 2*: By default, `recursive_directory_iterator` does not follow
 directory symlinks. To follow directory symlinks, specify `options` as
-`directory_options::follow_directory_symlink` — *end note*]
 ``` cpp
 recursive_directory_iterator(const recursive_directory_iterator& rhs);
 ```
-*Effects:* Constructs an object of class `recursive_directory_iterator`.
-*Postconditions:*
 - `options() == rhs.options()`
 - `depth() == rhs.depth()`
 - `recursion_pending() == rhs.recursion_pending()`
 ``` cpp
 recursive_directory_iterator(recursive_directory_iterator&& rhs) noexcept;
 ```
-*Effects:* Constructs an object of class `recursive_directory_iterator`.
-*Postconditions:* `options()`, `depth()`, and `recursion_pending()` have
-the values that `rhs.options()`, `rhs.depth()`, and
 `rhs.recursion_pending()`, respectively, had before the function call.
 ``` cpp
 recursive_directory_iterator& operator=(const recursive_directory_iterator& rhs);
 ```
 *Effects:* If `*this` and `rhs` are the same object, the member has no
 effect.
-*Postconditions:*
 - `options() == rhs.options()`
 - `depth() == rhs.depth()`
 - `recursion_pending() == rhs.recursion_pending()`
@@ -8852,12 +9680,12 @@ recursive_directory_iterator& operator=(recursive_directory_iterator&& rhs) noex
 ```
 *Effects:* If `*this` and `rhs` are the same object, the member has no
 effect.
-*Postconditions:* `options()`, `depth()`, and `recursion_pending()` have
-the values that `rhs.options()`, `rhs.depth()`, and
 `rhs.recursion_pending()`, respectively, had before the function call.
 *Returns:* `*this`.
 ``` cpp
@@ -8890,15 +9718,15 @@ subsequent to the prior construction or increment operation, otherwise
 *Throws:* Nothing.
 ``` cpp
 recursive_directory_iterator& operator++();
-recursive_directory_iterator& increment(error_code& ec) noexcept;
 ```
 *Effects:* As specified for the prefix increment operation of Input
-iterators ([[input.iterators]]), except that:
 - If there are no more entries at the current depth, then if
   `depth() != 0` iteration over the parent directory resumes; otherwise
   `*this = recursive_directory_iterator()`.
 - Otherwise if
@@ -8932,20 +9760,23 @@ void pop(error_code& ec);
 directory currently being iterated over, and continue iteration over the
 parent directory.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 void disable_recursion_pending();
 ```
-*Postconditions:* `recursion_pending() == false`.
 [*Note 4*: `disable_recursion_pending``()` is used to prevent unwanted
 recursion into a directory. — *end note*]
-#### `recursive_directory_iterator` non-member functions <a id="fs.rec.dir.itr.nonmembers">[[fs.rec.dir.itr.nonmembers]]</a>
 These functions enable use of `recursive_directory_iterator` with
 range-based for statements.
 ``` cpp
@@ -8964,11 +9795,11 @@ recursive_directory_iterator end(const recursive_directory_iterator&) noexcept;
 Filesystem operation functions query or modify files, including
 directories, in external storage.
 [*Note 1*: Because hardware failures, network failures, file system
-races ([[fs.def.race]]), and many other kinds of errors occur
 frequently in file system operations, users should be aware that any
 filesystem operation function, no matter how apparently innocuous, may
 encounter an error; see  [[fs.err.report]]. — *end note*]
 #### Absolute <a id="fs.op.absolute">[[fs.op.absolute]]</a>
@@ -8977,11 +9808,11 @@ encounter an error; see  [[fs.err.report]]. — *end note*]
 path absolute(const path& p);
 path absolute(const path& p, error_code& ec);
 ```
 *Effects:* Composes an absolute path referencing the same file system
-location as `p` according to the operating system ([[fs.conform.os]]).
 *Returns:* The composed path. The signature with argument `ec` returns
 `path()` if an error occurs.
 [*Note 1*: For the returned path, `rp`, `rp.is_absolute()` is `true`
@@ -8989,11 +9820,11 @@ unless an error occurs. — *end note*]
 *Throws:* As specified in  [[fs.err.report]].
 [*Note 2*: To resolve symlinks, or perform other sanitization which
 might require queries to secondary storage, such as hard disks, consider
-`canonical` ([[fs.op.canonical]]). — *end note*]
 [*Note 3*: Implementations are strongly encouraged to not query
 secondary storage, and not consider `!exists(p)` an
 error. — *end note*]
@@ -9003,22 +9834,19 @@ simply `current_path()/p`. For Windows-based operating systems,
 `GetFullPathNameW`. — *end example*]
 #### Canonical <a id="fs.op.canonical">[[fs.op.canonical]]</a>
 ``` cpp
-path canonical(const path& p, const path& base = current_path());
 path canonical(const path& p, error_code& ec);
-path canonical(const path& p, const path& base, error_code& ec);
 ```
-*Effects:* Converts `p`, which must exist, to an absolute path that has
-no symbolic link, *dot*, or *dot-dot* elements in its pathname in the
-generic format.
 *Returns:* A path that refers to the same file system object as
-`absolute(p, base)`. For the overload without a `base` argument, `base`
-is `current_path()`. Signatures with argument `ec` return `path()` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 *Remarks:* `!exists(p)` is an error.
@@ -9030,23 +9858,23 @@ void copy(const path& from, const path& to);
 ```
 *Effects:* Equivalent to `copy(from, to, copy_options::none)`.
 ``` cpp
-void copy(const path& from, const path& to, error_code& ec) noexcept;
 ```
 *Effects:* Equivalent to `copy(from, to, copy_options::none, ec)`.
 ``` cpp
 void copy(const path& from, const path& to, copy_options options);
 void copy(const path& from, const path& to, copy_options options,
-          error_code& ec) noexcept;
 ```
-*Requires:* At most one element from each option group
-([[fs.enum.copy.opts]]) is set in `options`.
 *Effects:* Before the first use of `f` and `t`:
 - If
   ``` cpp
@@ -9067,17 +9895,17 @@ void copy(const path& from, const path& to, copy_options options,
   `auto t = status(to)`.
 Effects are then as follows:
 - If `f.type()` or `t.type()` is an implementation-defined file
-  type ([[fs.enum.file_type]]), then the effects are
   *implementation-defined*.
 - Otherwise, an error is reported as specified in  [[fs.err.report]] if:
-  - `!exists(f)`, or
-  - `equivalent(from, to)`, or
-  - `is_other(f) || is_other(t)`, or
-  - `is_directory(f) && is_regular_file(t)`.
 - Otherwise, if `is_symlink(f)`, then:
   - If `(options & copy_options::skip_symlinks) != copy_options::none`
     then return.
   - Otherwise if
     ``` cpp
@@ -9097,24 +9925,36 @@ Effects are then as follows:
     `(options & copy_options::create_hard_links) != copy_options::none`,
     then create a hard link to the source file.
   - Otherwise, if `is_directory(t)`, then
     `copy_file(from, to/from.filename(), options)`.
   - Otherwise, `copy_file(from, to, options)`.
 - Otherwise, if
   ``` cpp
   is_directory(f) &&
   ((options & copy_options::recursive) != copy_options::none ||
    options == copy_options::none)
   ```
   then:
-  - If `!exists(t)`, then `create_directory(to, from)`.
   - Then, iterate over the files in `from`, as if by
     ``` cpp
     for (const directory_entry& x : directory_iterator(from))
-      copy(x.path(), to/x.path().filename(), options | copy_options::unspecified)
     ```
 - Otherwise, for the signature with argument `ec`, `ec.clear()`.
 - Otherwise, no effects.
 *Throws:* As specified in  [[fs.err.report]].
@@ -9163,62 +10003,61 @@ would result in:
     file3
 ```
 — *end example*]
-#### Copy file <a id="fs.op.copy_file">[[fs.op.copy_file]]</a>
 ``` cpp
 bool copy_file(const path& from, const path& to);
-bool copy_file(const path& from, const path& to, error_code& ec) noexcept;
 ```
 *Returns:* `copy_file(from, to, copy_options::none)` or
 `copy_file(from, to, copy_options::none, ec)`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool copy_file(const path& from, const path& to, copy_options options);
 bool copy_file(const path& from, const path& to, copy_options options,
-               error_code& ec) noexcept;
 ```
-*Requires:* At most one element from each option group
-([[fs.enum.copy.opts]]) is set in `options`.
 *Effects:* As follows:
-- Report a file already exists error as specified in  [[fs.err.report]]
- if:
-  - `!is_regular_file(from)`, or
-  - `exists(to)` and `!is_regular_file(to)`, or
-  - `exists(to)` and `equivalent(from, to)`, or
-  - `exists(to)` and
     ``` cpp
     (options & (copy_options::skip_existing |
                 copy_options::overwrite_existing |
                 copy_options::update_existing)) == copy_options::none
     ```
 - Otherwise, copy the contents and attributes of the file `from`
   resolves to, to the file `to` resolves to, if:
-  - `!exists(to)`, or
   - `(options & copy_options::overwrite_existing) != copy_options::none`,
     or
   - `(options & copy_options::update_existing) `` `` != copy_options::none`
     and `from` is more recent than `to`, determined as if by use of the
-    `last_write_time` function ([[fs.op.last_write_time]]).
 - Otherwise, no effects.
 *Returns:* `true` if the `from` file was copied, otherwise `false`. The
 signature with argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 *Complexity:* At most one direct or indirect invocation of `status(to)`.
-#### Copy symlink <a id="fs.op.copy_symlink">[[fs.op.copy_symlink]]</a>
 ``` cpp
 void copy_symlink(const path& existing_symlink, const path& new_symlink);
 void copy_symlink(const path& existing_symlink, const path& new_symlink,
                   error_code& ec) noexcept;
@@ -9230,86 +10069,78 @@ void copy_symlink(const path& existing_symlink, const path& new_symlink,
 respectively, where in each case *`function`* is `create_symlink` or
 `create_directory_symlink` as appropriate.
 *Throws:* As specified in  [[fs.err.report]].
-#### Create directories <a id="fs.op.create_directories">[[fs.op.create_directories]]</a>
 ``` cpp
 bool create_directories(const path& p);
-bool create_directories(const path& p, error_code& ec) noexcept;
 ```
-*Effects:* Establishes the postcondition by calling `create_directory()`
-for any element of `p` that does not exist.
-*Postconditions:* `is_directory(p)`.
-*Returns:* `true` if a new directory was created, otherwise `false`. The
-signature with argument `ec` returns `false` if an error occurs.
-*Throws:* As specified in  [[fs.err.report]].
-*Complexity:* 𝑂(n) where *n* is the number of elements of `p` that do
 not exist.
-#### Create directory <a id="fs.op.create_directory">[[fs.op.create_directory]]</a>
 ``` cpp
 bool create_directory(const path& p);
 bool create_directory(const path& p, error_code& ec) noexcept;
 ```
-*Effects:* Establishes the postcondition by attempting to create the
-directory `p` resolves to, as if by POSIX `mkdir()` with a second
-argument of `static_cast<int>(perms::all)`. Creation failure because `p`
-resolves to an existing directory shall not be treated as an error.
-*Postconditions:* `is_directory(p)`.
-*Returns:* `true` if a new directory was created, otherwise `false`. The
-signature with argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool create_directory(const path& p, const path& existing_p);
 bool create_directory(const path& p, const path& existing_p, error_code& ec) noexcept;
 ```
-*Effects:* Establishes the postcondition by attempting to create the
-directory `p` resolves to, with attributes copied from directory
-`existing_p`. The set of attributes copied is operating system
-dependent. Creation failure because `p` resolves to an existing
-directory shall not be treated as an error.
 [*Note 1*: For POSIX-based operating systems, the attributes are those
 copied by native API `stat(existing_p.c_str(), &attributes_stat)`
 followed by `mkdir(p.c_str(), attributes_stat.st_mode)`. For
 Windows-based operating systems, the attributes are those copied by
 native API
 `CreateDirectoryExW(existing_p.c_str(), p.c_str(), 0)`. — *end note*]
-*Postconditions:* `is_directory(p)`.
-*Returns:* `true` if a new directory was created, otherwise `false`. The
-signature with argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Create directory symlink <a id="fs.op.create_dir_symlk">[[fs.op.create_dir_symlk]]</a>
 ``` cpp
 void create_directory_symlink(const path& to, const path& new_symlink);
 void create_directory_symlink(const path& to, const path& new_symlink,
                               error_code& ec) noexcept;
 ```
 *Effects:* Establishes the postcondition, as if by POSIX `symlink()`.
-*Postconditions:* `new_symlink` resolves to a symbolic link file that
-contains an unspecified representation of `to`.
 *Throws:* As specified in  [[fs.err.report]].
 [*Note 1*: Some operating systems require symlink creation to identify
 that the link is to a directory. Portable code should use
@@ -9319,21 +10150,21 @@ that the link is to a directory. Portable code should use
 [*Note 2*: Some operating systems do not support symbolic links at all
 or support them only for regular files. Some file systems (such as the
 FAT file system) do not support symbolic links regardless of the
 operating system. — *end note*]
-#### Create hard link <a id="fs.op.create_hard_lk">[[fs.op.create_hard_lk]]</a>
 ``` cpp
 void create_hard_link(const path& to, const path& new_hard_link);
 void create_hard_link(const path& to, const path& new_hard_link,
                                       error_code& ec) noexcept;
 ```
 *Effects:* Establishes the postcondition, as if by POSIX `link()`.
-*Postconditions:*
 - `exists(to) && exists(new_hard_link) && equivalent(to, new_hard_link)`
 - The contents of the file or directory `to` resolves to are unchanged.
 *Throws:* As specified in  [[fs.err.report]].
@@ -9342,31 +10173,31 @@ void create_hard_link(const path& to, const path& new_hard_link,
 support them only for regular files. Some file systems (such as the FAT
 file system) do not support hard links regardless of the operating
 system. Some file systems limit the number of links per
 file. — *end note*]
-#### Create symlink <a id="fs.op.create_symlink">[[fs.op.create_symlink]]</a>
 ``` cpp
 void create_symlink(const path& to, const path& new_symlink);
 void create_symlink(const path& to, const path& new_symlink,
                     error_code& ec) noexcept;
 ```
 *Effects:* Establishes the postcondition, as if by POSIX `symlink()`.
-*Postconditions:* `new_symlink` resolves to a symbolic link file that
-contains an unspecified representation of `to`.
 *Throws:* As specified in  [[fs.err.report]].
 [*Note 1*: Some operating systems do not support symbolic links at all
 or support them only for regular files. Some file systems (such as the
 FAT file system) do not support symbolic links regardless of the
 operating system. — *end note*]
-#### Current path <a id="fs.op.current_path">[[fs.op.current_path]]</a>
 ``` cpp
 path current_path();
 path current_path(error_code& ec);
 ```
@@ -9384,22 +10215,21 @@ resolution for relative paths.
 [*Note 1*: The `current_path()` name was chosen to emphasize that the
 returned value is a path, not just a single directory
 name. — *end note*]
 [*Note 2*: The current path as returned by many operating systems is a
-dangerous global variable. It may be changed unexpectedly by a
-third-party or system library functions, or by another
-thread. — *end note*]
 ``` cpp
 void current_path(const path& p);
 void current_path(const path& p, error_code& ec) noexcept;
 ```
 *Effects:* Establishes the postcondition, as if by POSIX `chdir()`.
-*Postconditions:* `equivalent(p, current_path())`.
 *Throws:* As specified in  [[fs.err.report]].
 [*Note 3*: The current path for many operating systems is a dangerous
 global state. It may be changed unexpectedly by a third-party or system
@@ -9410,26 +10240,22 @@ library functions, or by another thread. — *end note*]
 ``` cpp
 bool equivalent(const path& p1, const path& p2);
 bool equivalent(const path& p1, const path& p2, error_code& ec) noexcept;
 ```
-Let `s1` and `s2` be `file_status`s, determined as if by `status(p1)`
-and `status(p2)`, respectively.
-*Effects:* Determines `s1` and `s2`. If
-`(!exists(s1) && !exists(s2)) || (is_other(s1) && is_other(s2))` an
-error is reported ([[fs.err.report]]).
-*Returns:* `true`, if `s1 == s2` and `p1` and `p2` resolve to the same
-file system entity, else `false`. The signature with argument `ec`
-returns `false` if an error occurs.
 Two paths are considered to resolve to the same file system entity if
 two candidate entities reside on the same device at the same location.
-This is determined as if by the values of the POSIX `stat` structure,
-obtained as if by `stat()` for the two paths, having equal `st_dev`
-values and equal `st_ino` values.
 *Throws:* As specified in  [[fs.err.report]].
 #### Exists <a id="fs.op.exists">[[fs.op.exists]]</a>
@@ -9452,31 +10278,33 @@ Let `s` be a `file_status`, determined as if by `status(p)` or
 *Returns:* `exists(s)`.
 *Throws:* As specified in  [[fs.err.report]].
-#### File size <a id="fs.op.file_size">[[fs.op.file_size]]</a>
 ``` cpp
 uintmax_t file_size(const path& p);
 uintmax_t file_size(const path& p, error_code& ec) noexcept;
 ```
 *Returns:*
-- If `!exists(p)` an error is reported ([[fs.err.report]]).
-- Otherwise, if `is_regular_file(p)`, the size in bytes of the file `p`
- resolves to, determined as if by the value of the POSIX `stat`
-  structure member `st_size` obtained as if by POSIX `stat()`.
 - Otherwise, the result is *implementation-defined*.
 The signature with argument `ec` returns `static_cast<uintmax_t>(-1)` if
 an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Hard link count <a id="fs.op.hard_lk_ct">[[fs.op.hard_lk_ct]]</a>
 ``` cpp
 uintmax_t hard_link_count(const path& p);
 uintmax_t hard_link_count(const path& p, error_code& ec) noexcept;
 ```
@@ -9484,11 +10312,11 @@ uintmax_t hard_link_count(const path& p, error_code& ec) noexcept;
 *Returns:* The number of hard links for `p`. The signature with argument
 `ec` returns `static_cast<uintmax_t>(-1)` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Is block file <a id="fs.op.is_block_file">[[fs.op.is_block_file]]</a>
 ``` cpp
 bool is_block_file(file_status s) noexcept;
 ```
@@ -9503,11 +10331,11 @@ bool is_block_file(const path& p, error_code& ec) noexcept;
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Is character file <a id="fs.op.is_char_file">[[fs.op.is_char_file]]</a>
 ``` cpp
 bool is_character_file(file_status s) noexcept;
 ```
@@ -9522,11 +10350,11 @@ bool is_character_file(const path& p, error_code& ec) noexcept;
 `is_character_file(status(p, ec))`, respectively.
 The signature with argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Is directory <a id="fs.op.is_directory">[[fs.op.is_directory]]</a>
 ``` cpp
 bool is_directory(file_status s) noexcept;
 ```
@@ -9541,15 +10369,15 @@ bool is_directory(const path& p, error_code& ec) noexcept;
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Is empty <a id="fs.op.is_empty">[[fs.op.is_empty]]</a>
 ``` cpp
 bool is_empty(const path& p);
-bool is_empty(const path& p, error_code& ec) noexcept;
 ```
 *Effects:*
 - Determine `file_status s`, as if by `status(p)` or `status(p, ec)`,
@@ -9569,11 +10397,11 @@ bool is_empty(const path& p, error_code& ec) noexcept;
     occurred.
   - Otherwise, return `sz == 0`.
 *Throws:* As specified in  [[fs.err.report]].
-#### Is fifo <a id="fs.op.is_fifo">[[fs.op.is_fifo]]</a>
 ``` cpp
 bool is_fifo(file_status s) noexcept;
 ```
@@ -9588,11 +10416,11 @@ bool is_fifo(const path& p, error_code& ec) noexcept;
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Is other <a id="fs.op.is_other">[[fs.op.is_other]]</a>
 ``` cpp
 bool is_other(file_status s) noexcept;
 ```
@@ -9608,11 +10436,11 @@ bool is_other(const path& p, error_code& ec) noexcept;
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Is regular file <a id="fs.op.is_regular_file">[[fs.op.is_regular_file]]</a>
 ``` cpp
 bool is_regular_file(file_status s) noexcept;
 ```
@@ -9623,11 +10451,11 @@ bool is_regular_file(const path& p);
 ```
 *Returns:* `is_regular_file(status(p))`.
 *Throws:* `filesystem_error` if `status(p)` would throw
-`filesystem_error.`
 ``` cpp
 bool is_regular_file(const path& p, error_code& ec) noexcept;
 ```
@@ -9638,11 +10466,11 @@ bool is_regular_file(const path& p, error_code& ec) noexcept;
 between cases, call the `status` function directly. — *end note*]
 *Returns:* `is_regular_file(status(p, ec))`. Returns `false` if an error
 occurs.
-#### Is socket <a id="fs.op.is_socket">[[fs.op.is_socket]]</a>
 ``` cpp
 bool is_socket(file_status s) noexcept;
 ```
@@ -9657,11 +10485,11 @@ bool is_socket(const path& p, error_code& ec) noexcept;
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Is symlink <a id="fs.op.is_symlink">[[fs.op.is_symlink]]</a>
 ``` cpp
 bool is_symlink(file_status s) noexcept;
 ```
@@ -9676,20 +10504,20 @@ bool is_symlink(const path& p, error_code& ec) noexcept;
 `is_symlink(symlink_status(p, ec))`, respectively. The signature with
 argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Last write time <a id="fs.op.last_write_time">[[fs.op.last_write_time]]</a>
 ``` cpp
 file_time_type last_write_time(const path& p);
 file_time_type last_write_time(const path& p, error_code& ec) noexcept;
 ```
 *Returns:* The time of last data modification of `p`, determined as if
-by the value of the POSIX `stat` structure member `st_mtime` obtained as
-if by POSIX `stat()`. The signature with argument `ec` returns
 `file_time_type::min()` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
@@ -9713,11 +10541,11 @@ granularity. — *end note*]
 void permissions(const path& p, perms prms, perm_options opts=perm_options::replace);
 void permissions(const path& p, perms prms, error_code& ec) noexcept;
 void permissions(const path& p, perms prms, perm_options opts, error_code& ec);
 ```
-*Requires:* Exactly one of the `perm_options` constants `replace`,
 `add`, or `remove` is present in `opts`.
 *Remarks:* The second signature behaves as if it had an additional
 parameter `perm_options` `opts` with an argument of
 `perm_options::replace`.
@@ -9761,11 +10589,11 @@ weakly_canonical(p, ec).lexically_proximate(weakly_canonical(base, ec));
 or `path()` at the first error occurrence, if any.
 *Throws:* As specified in  [[fs.err.report]].
-#### Read symlink <a id="fs.op.read_symlink">[[fs.op.read_symlink]]</a>
 ``` cpp
 path read_symlink(const path& p);
 path read_symlink(const path& p, error_code& ec);
 ```
@@ -9821,31 +10649,31 @@ bool remove(const path& p, error_code& ec) noexcept;
 as if by POSIX `remove()`.
 [*Note 1*: A symbolic link is itself removed, rather than the file it
 resolves to. — *end note*]
-*Postconditions:* `!exists(symlink_status(p))`.
 *Returns:* `false` if `p` did not exist, otherwise `true`. The signature
 with argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
-#### Remove all <a id="fs.op.remove_all">[[fs.op.remove_all]]</a>
 ``` cpp
 uintmax_t remove_all(const path& p);
-uintmax_t remove_all(const path& p, error_code& ec) noexcept;
 ```
 *Effects:* Recursively deletes the contents of `p` if it exists, then
 deletes file `p` itself, as if by POSIX `remove()`.
 [*Note 1*: A symbolic link is itself removed, rather than the file it
 resolves to. — *end note*]
-*Postconditions:* `!exists(symlink_status(p))`.
 *Returns:* The number of files removed. The signature with argument `ec`
 returns `static_cast< uintmax_t>(-1)` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
@@ -9874,23 +10702,22 @@ A symbolic link is itself renamed, rather than the file it resolves to.
 — *end note*]
 *Throws:* As specified in  [[fs.err.report]].
-#### Resize file <a id="fs.op.resize_file">[[fs.op.resize_file]]</a>
 ``` cpp
 void resize_file(const path& p, uintmax_t new_size);
 void resize_file(const path& p, uintmax_t new_size, error_code& ec) noexcept;
 ```
-*Postconditions:* `file_size(p) == new_size`.
 *Throws:* As specified in  [[fs.err.report]].
-*Remarks:* Achieves its postconditions as if by POSIX `truncate()`.
 #### Space <a id="fs.op.space">[[fs.op.space]]</a>
 ``` cpp
 space_info space(const path& p);
 space_info space(const path& p, error_code& ec) noexcept;
@@ -9989,27 +10816,27 @@ determined as if by converting the `st_mode` member of the obtained
   - Otherwise, if the attributes indicate a fifo or pipe file, as if by
     POSIX `S_ISFIFO`, returns `file_status(file_type::fifo, prms)`.
   - Otherwise, if the attributes indicate a socket, as if by POSIX
     `S_ISSOCK`, returns `file_status(file_type::socket, prms)`.
   - Otherwise, if the attributes indicate an implementation-defined file
-    type ([[fs.enum.file_type]]), returns
     `file_status(file_type::`*`A`*`, prms)`, where *A* is the constant
     for the *implementation-defined* file type.
   - Otherwise, returns `file_status(file_type::unknown, prms)`.
 *Remarks:* If a symbolic link is encountered during pathname resolution,
 pathname resolution continues using the contents of the symbolic link.
-#### Status known <a id="fs.op.status_known">[[fs.op.status_known]]</a>
 ``` cpp
 bool status_known(file_status s) noexcept;
 ```
 *Returns:* `s.type() != file_type::none`.
-#### Symlink status <a id="fs.op.symlink_status">[[fs.op.symlink_status]]</a>
 ``` cpp
 file_status symlink_status(const path& p);
 file_status symlink_status(const path& p, error_code& ec) noexcept;
 ```
@@ -10029,20 +10856,23 @@ indicate a symbolic link, as if by POSIX `S_ISLNK`, returns
 *Remarks:* Pathname resolution terminates if `p` names a symbolic link.
 *Throws:* As specified in  [[fs.err.report]].
-#### Temporary directory path <a id="fs.op.temp_dir_path">[[fs.op.temp_dir_path]]</a>
 ``` cpp
 path temp_directory_path();
 path temp_directory_path(error_code& ec);
 ```
-*Returns:* An unspecifed directory path suitable for temporary files. An
-error shall be reported if `!exists(p) || !is_directory(p)`, where `p`
-is the path to be returned. The signature with argument `ec` returns
 `path()` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 [*Example 1*: For POSIX-based operating systems, an implementation
@@ -10050,36 +10880,33 @@ might return the path supplied by the first environment variable found
 in the list TMPDIR, TMP, TEMP, TEMPDIR, or if none of these are found,
 `"/tmp"`. For Windows-based operating systems, an implementation might
 return the path reported by the Windows `GetTempPath` API
 function. — *end example*]
-#### Weakly canonical <a id="fs.op.weakly_canonical">[[fs.op.weakly_canonical]]</a>
 ``` cpp
 path weakly_canonical(const path& p);
 path weakly_canonical(const path& p, error_code& ec);
 ```
 *Returns:* `p` with symlinks resolved and the result
-normalized ([[fs.def.normal.form]]).
 *Effects:* Using `status(p)` or `status(p, ec)`, respectively, to
 determine existence, return a path composed by `operator/=` from the
-result of calling `canonical()` without a `base` argument and with a
-path argument composed of the leading elements of `p` that exist, if
-any, followed by the elements of `p` that do not exist, if any. For the
-first form, `canonical()` is called without an `error_code` argument.
-For the second form, `canonical()` is called with `ec` as an
-`error_code` argument, and `path()` is returned at the first error
-occurrence, if any.
-*Postconditions:* The returned path is in normal
-form ([[fs.def.normal.form]]).
-*Remarks:* Implementations are encouraged to avoid unnecessary
-normalization such as when `canonical` has already been called on the
-entirety of `p`.
 *Throws:* As specified in  [[fs.err.report]].
 ## C library files <a id="c.files">[[c.files]]</a>
@@ -10109,11 +10936,11 @@ namespace std {
 #define stdin see below
 #define stdout see below
 namespace std {
   int remove(const char* filename);
-  int rename(const char* old, const char* new);
   FILE* tmpfile();
   char* tmpnam(char* s);
   int fclose(FILE* stream);
   int fflush(FILE* stream);
   FILE* fopen(const char* filename, const char* mode);
@@ -10160,14 +10987,14 @@ namespace std {
 The contents and meaning of the header `<cstdio>` are the same as the C
 standard library header `<stdio.h>`.
 Calls to the function `tmpnam` with an argument that is a null pointer
-value may introduce a data race ([[res.on.data.races]]) with other
-calls to `tmpnam` with an argument that is a null pointer value.
-ISO C 7.21.
 ### Header `<cinttypes>` synopsis <a id="cinttypes.syn">[[cinttypes.syn]]</a>
 ``` cpp
 #include <cstdint>  // see [cstdint.syn]
@@ -10246,145 +11073,139 @@ namespace std {
 The contents and meaning of the header `<cinttypes>` are the same as the
 C standard library header `<inttypes.h>`, with the following changes:
 - The header `<cinttypes>` includes the header `<cstdint>` instead of
   `<stdint.h>`, and
-- if and only if the type `intmax_t` designates an extended integer
- type ([[basic.fundamental]]), the following function signatures are
-  added:
   ``` cpp
   intmax_t abs(intmax_t);
   imaxdiv_t div(intmax_t, intmax_t);
   ```
   which shall have the same semantics as the function signatures
   `intmax_t imaxabs(intmax_t)` and
   `imaxdiv_t imaxdiv(intmax_t, intmax_t)`, respectively.
-ISO C 7.8.
 <!-- Link reference definitions -->
 [adjustfield.manip]: #adjustfield.manip
-[allocator.requirements]: library.md#allocator.requirements
 [basefield.manip]: #basefield.manip
 [basic.fundamental]: basic.md#basic.fundamental
 [basic.ios.cons]: #basic.ios.cons
 [basic.ios.members]: #basic.ios.members
 [basic.start.main]: basic.md#basic.start.main
 [bidirectional.iterators]: iterators.md#bidirectional.iterators
 [bitmask.types]: library.md#bitmask.types
 [c.files]: #c.files
 [cinttypes.syn]: #cinttypes.syn
 [cstdio.syn]: #cstdio.syn
 [defns.ntcts]: library.md#defns.ntcts
 [enumerated.types]: library.md#enumerated.types
 [error.reporting]: #error.reporting
 [ext.manip]: #ext.manip
-[fig:streampos]: #fig:streampos
 [file.streams]: #file.streams
 [filebuf]: #filebuf
 [filebuf.assign]: #filebuf.assign
 [filebuf.cons]: #filebuf.cons
 [filebuf.members]: #filebuf.members
 [filebuf.virtuals]: #filebuf.virtuals
-[filesystem_error.members]: #filesystem_error.members
 [filesystems]: #filesystems
 [floatfield.manip]: #floatfield.manip
 [fmtflags.manip]: #fmtflags.manip
 [fmtflags.state]: #fmtflags.state
 [fpos]: #fpos
 [fpos.members]: #fpos.members
 [fpos.operations]: #fpos.operations
-[fs.class.directory_entry]: #fs.class.directory_entry
-[fs.class.directory_iterator]: #fs.class.directory_iterator
-[fs.class.file_status]: #fs.class.file_status
-[fs.class.filesystem_error]: #fs.class.filesystem_error
 [fs.class.path]: #fs.class.path
 [fs.class.rec.dir.itr]: #fs.class.rec.dir.itr
 [fs.conform.9945]: #fs.conform.9945
 [fs.conform.os]: #fs.conform.os
 [fs.conformance]: #fs.conformance
-[fs.def.absolute.path]: #fs.def.absolute.path
-[fs.def.filename]: #fs.def.filename
-[fs.def.link]: #fs.def.link
-[fs.def.native]: #fs.def.native
-[fs.def.native.encode]: #fs.def.native.encode
-[fs.def.normal.form]: #fs.def.normal.form
-[fs.def.osdep]: #fs.def.osdep
-[fs.def.path]: #fs.def.path
-[fs.def.pathname]: #fs.def.pathname
-[fs.def.pathres]: #fs.def.pathres
-[fs.def.race]: #fs.def.race
-[fs.def.symlink]: #fs.def.symlink
-[fs.definitions]: #fs.definitions
 [fs.dir.entry.cons]: #fs.dir.entry.cons
 [fs.dir.entry.mods]: #fs.dir.entry.mods
 [fs.dir.entry.obs]: #fs.dir.entry.obs
 [fs.dir.itr.members]: #fs.dir.itr.members
 [fs.dir.itr.nonmembers]: #fs.dir.itr.nonmembers
 [fs.enum]: #fs.enum
 [fs.enum.copy.opts]: #fs.enum.copy.opts
 [fs.enum.dir.opts]: #fs.enum.dir.opts
-[fs.enum.file_type]: #fs.enum.file_type
 [fs.enum.path.format]: #fs.enum.path.format
 [fs.enum.perm.opts]: #fs.enum.perm.opts
 [fs.enum.perms]: #fs.enum.perms
 [fs.err.report]: #fs.err.report
-[fs.file_status.cons]: #fs.file_status.cons
-[fs.file_status.mods]: #fs.file_status.mods
-[fs.file_status.obs]: #fs.file_status.obs
 [fs.filesystem.syn]: #fs.filesystem.syn
 [fs.general]: #fs.general
 [fs.norm.ref]: #fs.norm.ref
 [fs.op.absolute]: #fs.op.absolute
 [fs.op.canonical]: #fs.op.canonical
 [fs.op.copy]: #fs.op.copy
-[fs.op.copy_file]: #fs.op.copy_file
-[fs.op.copy_symlink]: #fs.op.copy_symlink
-[fs.op.create_dir_symlk]: #fs.op.create_dir_symlk
-[fs.op.create_directories]: #fs.op.create_directories
-[fs.op.create_directory]: #fs.op.create_directory
-[fs.op.create_hard_lk]: #fs.op.create_hard_lk
-[fs.op.create_symlink]: #fs.op.create_symlink
-[fs.op.current_path]: #fs.op.current_path
 [fs.op.equivalent]: #fs.op.equivalent
 [fs.op.exists]: #fs.op.exists
-[fs.op.file_size]: #fs.op.file_size
 [fs.op.funcs]: #fs.op.funcs
-[fs.op.hard_lk_ct]: #fs.op.hard_lk_ct
-[fs.op.is_block_file]: #fs.op.is_block_file
-[fs.op.is_char_file]: #fs.op.is_char_file
-[fs.op.is_directory]: #fs.op.is_directory
-[fs.op.is_empty]: #fs.op.is_empty
-[fs.op.is_fifo]: #fs.op.is_fifo
-[fs.op.is_other]: #fs.op.is_other
-[fs.op.is_regular_file]: #fs.op.is_regular_file
-[fs.op.is_socket]: #fs.op.is_socket
-[fs.op.is_symlink]: #fs.op.is_symlink
-[fs.op.last_write_time]: #fs.op.last_write_time
 [fs.op.permissions]: #fs.op.permissions
 [fs.op.proximate]: #fs.op.proximate
-[fs.op.read_symlink]: #fs.op.read_symlink
 [fs.op.relative]: #fs.op.relative
 [fs.op.remove]: #fs.op.remove
-[fs.op.remove_all]: #fs.op.remove_all
 [fs.op.rename]: #fs.op.rename
-[fs.op.resize_file]: #fs.op.resize_file
 [fs.op.space]: #fs.op.space
 [fs.op.status]: #fs.op.status
-[fs.op.status_known]: #fs.op.status_known
-[fs.op.symlink_status]: #fs.op.symlink_status
-[fs.op.temp_dir_path]: #fs.op.temp_dir_path
-[fs.op.weakly_canonical]: #fs.op.weakly_canonical
 [fs.path.append]: #fs.path.append
 [fs.path.assign]: #fs.path.assign
 [fs.path.compare]: #fs.path.compare
 [fs.path.concat]: #fs.path.concat
 [fs.path.construct]: #fs.path.construct
 [fs.path.cvt]: #fs.path.cvt
 [fs.path.decompose]: #fs.path.decompose
-[fs.path.factory]: #fs.path.factory
 [fs.path.fmt.cvt]: #fs.path.fmt.cvt
 [fs.path.gen]: #fs.path.gen
 [fs.path.generic]: #fs.path.generic
 [fs.path.generic.obs]: #fs.path.generic.obs
 [fs.path.io]: #fs.path.io
@@ -10412,28 +11233,30 @@ ISO C 7.8.
 [ifstream.members]: #ifstream.members
 [input.iterators]: iterators.md#input.iterators
 [input.output]: #input.output
 [input.output.general]: #input.output.general
 [input.streams]: #input.streams
-[intro.multithread]: intro.md#intro.multithread
 [iomanip.syn]: #iomanip.syn
 [ios]: #ios
 [ios.base]: #ios.base
 [ios.base.callback]: #ios.base.callback
 [ios.base.cons]: #ios.base.cons
 [ios.base.locales]: #ios.base.locales
 [ios.base.storage]: #ios.base.storage
 [ios.members.static]: #ios.members.static
 [ios.overview]: #ios.overview
 [ios.syn]: #ios.syn
 [ios.types]: #ios.types
-[ios::Init]: #ios::Init
-[ios::failure]: #ios::failure
-[ios::fmtflags]: #ios::fmtflags
-[ios::iostate]: #ios::iostate
-[ios::openmode]: #ios::openmode
-[ios::seekdir]: #ios::seekdir
 [iosfwd.syn]: #iosfwd.syn
 [iostate.flags]: #iostate.flags
 [iostream.assign]: #iostream.assign
 [iostream.cons]: #iostream.cons
 [iostream.dest]: #iostream.dest
@@ -10446,32 +11269,34 @@ ISO C 7.8.
 [iostream.syn]: #iostream.syn
 [iostreamclass]: #iostreamclass
 [iostreams.base]: #iostreams.base
 [iostreams.limits.pos]: #iostreams.limits.pos
 [iostreams.requirements]: #iostreams.requirements
 [iostreams.threadsafety]: #iostreams.threadsafety
 [istream]: #istream
 [istream.assign]: #istream.assign
 [istream.cons]: #istream.cons
 [istream.extractors]: #istream.extractors
 [istream.formatted]: #istream.formatted
 [istream.formatted.arithmetic]: #istream.formatted.arithmetic
 [istream.formatted.reqmts]: #istream.formatted.reqmts
 [istream.manip]: #istream.manip
 [istream.rvalue]: #istream.rvalue
 [istream.syn]: #istream.syn
 [istream.unformatted]: #istream.unformatted
-[istream::sentry]: #istream::sentry
 [istringstream]: #istringstream
 [istringstream.assign]: #istringstream.assign
 [istringstream.cons]: #istringstream.cons
 [istringstream.members]: #istringstream.members
 [lex.charset]: lex.md#lex.charset
 [locale.codecvt.virtuals]: localization.md#locale.codecvt.virtuals
 [locale.num.get]: localization.md#locale.num.get
 [narrow.stream.objects]: #narrow.stream.objects
-[numeric.limits]: language.md#numeric.limits
 [ofstream]: #ofstream
 [ofstream.assign]: #ofstream.assign
 [ofstream.cons]: #ofstream.cons
 [ofstream.members]: #ofstream.members
 [ostream]: #ostream
@@ -10483,13 +11308,13 @@ ISO C 7.8.
 [ostream.inserters.arithmetic]: #ostream.inserters.arithmetic
 [ostream.inserters.character]: #ostream.inserters.character
 [ostream.manip]: #ostream.manip
 [ostream.rvalue]: #ostream.rvalue
 [ostream.seeks]: #ostream.seeks
 [ostream.syn]: #ostream.syn
 [ostream.unformatted]: #ostream.unformatted
-[ostream::sentry]: #ostream::sentry
 [ostringstream]: #ostringstream
 [ostringstream.assign]: #ostringstream.assign
 [ostringstream.cons]: #ostringstream.cons
 [ostringstream.members]: #ostringstream.members
 [output.streams]: #output.streams
@@ -10525,60 +11350,49 @@ ISO C 7.8.
 [string.streams]: #string.streams
 [stringbuf]: #stringbuf
 [stringbuf.assign]: #stringbuf.assign
 [stringbuf.cons]: #stringbuf.cons
 [stringbuf.members]: #stringbuf.members
 [stringbuf.virtuals]: #stringbuf.virtuals
 [strings]: strings.md#strings
 [stringstream]: #stringstream
 [stringstream.assign]: #stringstream.assign
 [stringstream.cons]: #stringstream.cons
 [stringstream.members]: #stringstream.members
-[tab:enum.path.format]: #tab:enum.path.format
-[tab:enum.perm_options]: #tab:enum.perm_options
-[tab:filesystem_error.1]: #tab:filesystem_error.1
-[tab:filesystem_error.2]: #tab:filesystem_error.2
-[tab:filesystem_error.3]: #tab:filesystem_error.3
-[tab:fs.enum.copy_options]: #tab:fs.enum.copy_options
-[tab:fs.enum.directory_options]: #tab:fs.enum.directory_options
-[tab:fs.enum.file_type]: #tab:fs.enum.file_type
-[tab:fs.enum.perms]: #tab:fs.enum.perms
-[tab:iostreams.basicios.init.effects]: #tab:iostreams.basicios.init.effects
-[tab:iostreams.copyfmt.effects]: #tab:iostreams.copyfmt.effects
-[tab:iostreams.file.open.modes]: #tab:iostreams.file.open.modes
-[tab:iostreams.fmtflags.constants]: #tab:iostreams.fmtflags.constants
-[tab:iostreams.fmtflags.effects]: #tab:iostreams.fmtflags.effects
-[tab:iostreams.iostate.effects]: #tab:iostreams.iostate.effects
-[tab:iostreams.lib.summary]: #tab:iostreams.lib.summary
-[tab:iostreams.newoff.values]: #tab:iostreams.newoff.values
-[tab:iostreams.openmode.effects]: #tab:iostreams.openmode.effects
-[tab:iostreams.position.requirements]: #tab:iostreams.position.requirements
-[tab:iostreams.seekdir.effects]: #tab:iostreams.seekdir.effects
-[tab:iostreams.seekoff.effects]: #tab:iostreams.seekoff.effects
-[tab:iostreams.seekoff.positioning]: #tab:iostreams.seekoff.positioning
 [temp.deduct]: temp.md#temp.deduct
-[time.clock.req]: utilities.md#time.clock.req
 [wide.stream.objects]: #wide.stream.objects
 [^1]: It is the implementation’s responsibility to implement headers so
     that including `<iosfwd>` and other headers does not violate the
     rules about multiple occurrences of default arguments.
-[^2]: If it is possible for them to do so, implementations are
- encouraged to initialize the objects earlier than required.
-[^3]: Constructors and destructors for static objects can access these
-    objects to read input from `stdin` or write output to `stdout` or
-    `stderr`.
 [^4]: Typically `long long`.
 [^5]: `streamsize` is used in most places where ISO C would use
-    `size_t`. Most of the uses of `streamsize` could use `size_t`,
-    except for the `strstreambuf` constructors, which require negative
-    values. It should probably be the signed type corresponding to
-    `size_t` (which is what Posix.2 calls `ssize_t`).
 [^6]: This implies that operations on a standard iostream object can be
     mixed arbitrarily with operations on the corresponding stdio stream.
     In practical terms, synchronization usually means that a standard
     iostream object and a standard stdio object share a buffer.
@@ -10586,13 +11400,13 @@ ISO C 7.8.
 [^7]: An implementation is free to implement both the integer array
     pointed at by `iarray` and the pointer array pointed at by `parray`
     as sparse data structures, possibly with a one-element cache for
     each.
-[^8]: for example, because it cannot allocate space.
-[^9]: for example, because it cannot allocate space.
 [^10]: This suggests an infinite amount of copying, but the
     implementation can keep track of the maximum element of the arrays
     that is nonzero.
@@ -10628,22 +11442,22 @@ ISO C 7.8.
 [^18]: This will be possible only in functions that are part of the
     library. The semantics of the constructor used in user code is as
     specified.
-[^19]: The sentry constructor and destructor can also perform additional
-    implementation-dependent operations.
-[^20]: This is done without causing an `ios::failure` to be thrown.
 [^21]: See, for example, the function signature
-    `ws(basic_istream&)` ([[istream.manip]]).
 [^22]: See, for example, the function signature
-    `dec(ios_base&)` ([[basefield.manip]]).
-[^23]: This is done without causing an `ios::failure` to be thrown.
 [^24]: Note that this function is not overloaded on types `signed char`
     and `unsigned char`.
 [^25]: Note that this function is not overloaded on types `signed char`
@@ -10669,19 +11483,19 @@ ISO C 7.8.
     function can determine that no synchronization is necessary.
 [^32]: The `sentry` constructor and destructor can also perform
     additional implementation-dependent operations.
-[^33]: without causing an `ios::failure` to be thrown.
 [^34]: See, for example, the function signature
-    `endl(basic_ostream&)` ([[ostream.manip]]).
 [^35]: See, for example, the function signature
-    `dec(ios_base&)` ([[basefield.manip]]).
-[^36]: without causing an `ios::failure` to be thrown.
 [^37]: Note that this function is not overloaded on types `signed char`
     and `unsigned char`.
 [^38]: Note that this function is not overloaded on types `signed char`
@@ -10696,11 +11510,11 @@ ISO C 7.8.
     `basic_ostream<charT, traits>` object `cout` (the same as
     `cout << noshowbase`).
 [^40]: The macro `SEEK_END` is defined, and the function signatures
     `fopen(const char*, const char*)` and `fseek(FILE*, long, int)` are
-    declared, in `<cstdio>` ([[cstdio.syn]]).
 [^41]: POSIX® is a registered trademark of The IEEE. Windows® is a
     registered trademark of Microsoft Corporation. This information is
     given for the convenience of users of this document and does not
     constitute an endorsement by ISO or IEC of these products.

 The following subclauses describe requirements for stream parameters,
 and components for forward declarations of iostreams, predefined
 iostreams objects, base iostreams classes, stream buffering, stream
 formatting and manipulators, string streams, and file streams, as
+summarized in [[iostreams.summary]].
+**Table: Input/output library summary** <a id="iostreams.summary">[iostreams.summary]</a>
 | Subclause                  |                             | Header                                |
+| -------------------------- | --------------------------- | ------------------------------------- |
 | [[iostreams.requirements]] | Requirements                |                                       |
 | [[iostream.forward]]       | Forward declarations        | `<iosfwd>`                            |
 | [[iostream.objects]]       | Standard iostream objects   | `<iostream>`                          |
 | [[iostreams.base]]         | Iostreams base classes      | `<ios>`                               |
 | [[stream.buffers]]         | Stream buffers              | `<streambuf>`                         |
+| [[iostream.format]]        | Formatting and manipulators | `<iomanip>`, `<istream>`, `<ostream>` |
 | [[string.streams]]         | String streams              | `<sstream>`                           |
 | [[file.streams]]           | File streams                | `<fstream>`                           |
+| [[syncstream]]             | Synchronized output streams | `<syncstream>`                        |
 | [[filesystems]]            | File systems                | `<filesystem>`                        |
+| [[c.files]]                | C library files             | `<cstdio>`, `<cinttypes>`             |
+[*Note 1*: Figure [[fig:iostreams.streampos]] illustrates
+relationships among various types described in this clause. A line from
+**A** to **B** indicates that **A** is an alias (e.g., a typedef) for
+**B** or that **A** is defined in terms of **B**.
+<a id="fig:iostreams.streampos"></a>
+![Stream position, offset, and size types \[fig:iostreams.streampos\]](images/figstreampos.svg)
+ — *end note*]
 ## Iostreams requirements <a id="iostreams.requirements">[[iostreams.requirements]]</a>
 ### Imbue limitations <a id="iostream.limits.imbue">[[iostream.limits.imbue]]</a>
+No function described in [[input.output]] except for `ios_base::imbue`
+and `basic_filebuf::pubimbue` causes any instance of `basic_ios::imbue`
+or `basic_streambuf::imbue` to be called. If any user function called
+from a function declared in [[input.output]] or as an overriding virtual
+function of any class declared in [[input.output]] calls `imbue`, the
+behavior is undefined.
 ### Positioning type limitations <a id="iostreams.limits.pos">[[iostreams.limits.pos]]</a>
+The classes of [[input.output]] with template arguments `charT` and
+`traits` behave as described if `traits::pos_type` and
 `traits::off_type` are `streampos` and `streamoff` respectively. Except
 as noted explicitly below, their behavior when `traits::pos_type` and
 `traits::off_type` are other types is *implementation-defined*.
+In the classes of [[input.output]], a template parameter with name
+`charT` represents a member of the set of types containing `char`,
 `wchar_t`, and any other *implementation-defined* character types that
+meet the requirements for a character on which any of the iostream
 components can be instantiated.
 ### Thread safety <a id="iostreams.threadsafety">[[iostreams.threadsafety]]</a>
+Concurrent access to a stream object ([[string.streams]],
+[[file.streams]]), stream buffer object [[stream.buffers]], or C Library
+stream [[c.files]] by multiple threads may result in a data race
+[[intro.multithread]] unless otherwise specified [[iostream.objects]].
+[*Note 1*: Data races result in undefined behavior
+[[intro.multithread]]. — *end note*]
 If one thread makes a library call *a* that writes a value to a stream
 and, as a result, another thread reads this value from the stream
 through a library call *b* such that this does not result in a data
 race, then *a*’s write synchronizes with *b*’s read.
 ### Header `<iosfwd>` synopsis <a id="iosfwd.syn">[[iosfwd.syn]]</a>
 ``` cpp
 namespace std {
+  template<class charT> struct char_traits;
+  template<> struct char_traits<char>;
+  template<> struct char_traits<char8_t>;
+  template<> struct char_traits<char16_t>;
+  template<> struct char_traits<char32_t>;
+  template<> struct char_traits<wchar_t>;
   template<class T> class allocator;
   template<class charT, class traits = char_traits<charT>>
     class basic_ios;
   template<class charT, class traits = char_traits<charT>>
     class basic_ofstream;
   template<class charT, class traits = char_traits<charT>>
     class basic_fstream;
+  template<class charT, class traits = char_traits<charT>,
+           class Allocator = allocator<charT>>
+    class basic_syncbuf;
+  template<class charT, class traits = char_traits<charT>,
+           class Allocator = allocator<charT>>
+    class basic_osyncstream;
   template<class charT, class traits = char_traits<charT>>
     class istreambuf_iterator;
   template<class charT, class traits = char_traits<charT>>
     class ostreambuf_iterator;
   using filebuf  = basic_filebuf<char>;
   using ifstream = basic_ifstream<char>;
   using ofstream = basic_ofstream<char>;
   using fstream  = basic_fstream<char>;
+  using syncbuf = basic_syncbuf<char>;
+  using osyncstream = basic_osyncstream<char>;
   using wstreambuf = basic_streambuf<wchar_t>;
   using wistream   = basic_istream<wchar_t>;
   using wostream   = basic_ostream<wchar_t>;
   using wiostream  = basic_iostream<wchar_t>;
   using wfilebuf  = basic_filebuf<wchar_t>;
   using wifstream = basic_ifstream<wchar_t>;
   using wofstream = basic_ofstream<wchar_t>;
   using wfstream  = basic_fstream<wchar_t>;
+  using wsyncbuf = basic_syncbuf<wchar_t>;
+  using wosyncstream = basic_osyncstream<wchar_t>;
   template<class state> class fpos;
   using streampos  = fpos<char_traits<char>::state_type>;
   using wstreampos = fpos<char_traits<wchar_t>::state_type>;
+  using u8streampos = fpos<char_traits<char8_t>::state_type>;
+  using u16streampos = fpos<char_traits<char16_t>::state_type>;
+  using u32streampos = fpos<char_traits<char32_t>::state_type>;
 }
 ```
 Default template arguments are described as appearing both in `<iosfwd>`
 and in the synopsis of other headers but it is well-formed to include
 `basic_ostream`, and class templates derived from them. `basic_iostream`
 is a class template derived from both `basic_istream<charT, traits>` and
 `basic_ostream<charT, traits>`.
 The class template specialization `basic_streambuf<charT, traits>`
+serves as a base class for class templates `basic_stringbuf`,
+`basic_filebuf`, and `basic_syncbuf`.
 The class template specialization `basic_istream<charT, traits>` serves
 as a base class for class templates `basic_istringstream` and
 `basic_ifstream`.
 The class template specialization `basic_ostream<charT, traits>` serves
+as a base class for class templates `basic_ostringstream`,
+`basic_ofstream`, and `basic_osyncstream`.
 The class template specialization `basic_iostream<charT, traits>` serves
 as a base class for class templates `basic_stringstream` and
 `basic_fstream`.
+[*Note 1*: For each of the class templates above, the program is
+ill-formed if `traits::char_type` is not the same type as `charT`
+[[char.traits]]. — *end note*]
 Other *typedef-name*s define instances of class templates specialized
 for `char` or `wchar_t` types.
 Specializations of the class template `fpos` are used for specifying
 file position information.
+[*Example 1*: The types `streampos` and `wstreampos` are used for
+positioning streams specialized on `char` and `wchar_t`
+respectively. — *end example*]
+[*Note 2*: This synopsis suggests a circularity between `streampos` and
 `char_traits<char>`. An implementation can avoid this circularity by
+substituting equivalent types. — *end note*]
 ## Standard iostream objects <a id="iostream.objects">[[iostream.objects]]</a>
 ### Header `<iostream>` synopsis <a id="iostream.syn">[[iostream.syn]]</a>
 ```
 ### Overview <a id="iostream.objects.overview">[[iostream.objects.overview]]</a>
 In this Clause, the type name `FILE` refers to the type `FILE` declared
+in `<cstdio>`.
 The header `<iostream>` declares objects that associate objects with the
+standard C streams provided for by the functions declared in `<cstdio>`,
+and includes all the headers necessary to use these objects.
 The objects are constructed and the associations are established at some
 time prior to or during the first time an object of class
 `ios_base::Init` is constructed, and in any case before the body of
+`main` [[basic.start.main]] begins execution.[^2] The objects are not
 destroyed during program execution.[^3] The results of including
 `<iostream>` in a translation unit shall be as if `<iostream>` defined
 an instance of `ios_base::Init` with static storage duration.
 Mixing operations on corresponding wide- and narrow-character streams
 follows the same semantics as mixing such operations on `FILE`s, as
 specified in the C standard library.
+Concurrent access to a synchronized [[ios.members.static]] standard
+iostream object’s formatted and unformatted input [[istream]] and output
+[[ostream]] functions or a standard C stream by multiple threads does
+not result in a data race [[intro.multithread]].
 [*Note 1*: Users must still synchronize concurrent use of these objects
 and streams by multiple threads if they wish to avoid interleaved
 characters. — *end note*]
+See also: ISO C 7.21.2
 ### Narrow stream objects <a id="narrow.stream.objects">[[narrow.stream.objects]]</a>
 ``` cpp
 istream cin;
 ```
 The object `cin` controls input from a stream buffer associated with the
+object `stdin`, declared in `<cstdio>`.
 After the object `cin` is initialized, `cin.tie()` returns `&cout`. Its
+state is otherwise the same as required for `basic_ios<char>::init`
+[[basic.ios.cons]].
 ``` cpp
 ostream cout;
 ```
 The object `cout` controls output to a stream buffer associated with the
+object `stdout`, declared in `<cstdio>`.
 ``` cpp
 ostream cerr;
 ```
 The object `cerr` controls output to a stream buffer associated with the
+object `stderr`, declared in `<cstdio>`.
 After the object `cerr` is initialized, `cerr.flags() & unitbuf` is
 nonzero and `cerr.tie()` returns `&cout`. Its state is otherwise the
+same as required for `basic_ios<char>::init` [[basic.ios.cons]].
 ``` cpp
 ostream clog;
 ```
 The object `clog` controls output to a stream buffer associated with the
+object `stderr`, declared in `<cstdio>`.
 ### Wide stream objects <a id="wide.stream.objects">[[wide.stream.objects]]</a>
 ``` cpp
 wistream wcin;
 ```
 The object `wcin` controls input from a stream buffer associated with
+the object `stdin`, declared in `<cstdio>`.
 After the object `wcin` is initialized, `wcin.tie()` returns `&wcout`.
 Its state is otherwise the same as required for
+`basic_ios<wchar_t>::init` [[basic.ios.cons]].
 ``` cpp
 wostream wcout;
 ```
 The object `wcout` controls output to a stream buffer associated with
+the object `stdout`, declared in `<cstdio>`.
 ``` cpp
 wostream wcerr;
 ```
 The object `wcerr` controls output to a stream buffer associated with
+the object `stderr`, declared in `<cstdio>`.
 After the object `wcerr` is initialized, `wcerr.flags() & unitbuf` is
 nonzero and `wcerr.tie()` returns `&wcout`. Its state is otherwise the
+same as required for `basic_ios<wchar_t>::init` [[basic.ios.cons]].
 ``` cpp
 wostream wclog;
 ```
 The object `wclog` controls output to a stream buffer associated with
+the object `stderr`, declared in `<cstdio>`.
 ## Iostreams base classes <a id="iostreams.base">[[iostreams.base]]</a>
 ### Header `<ios>` synopsis <a id="ios.syn">[[ios.syn]]</a>
 namespace std {
   class ios_base {
   public:
     class failure;              // see below
+    // [ios.fmtflags], fmtflags
     using fmtflags = T1;
     static constexpr fmtflags boolalpha = unspecified;
     static constexpr fmtflags dec = unspecified;
     static constexpr fmtflags fixed = unspecified;
     static constexpr fmtflags hex = unspecified;
     static constexpr fmtflags uppercase = unspecified;
     static constexpr fmtflags adjustfield = see below;
     static constexpr fmtflags basefield = see below;
     static constexpr fmtflags floatfield = see below;
+    // [ios.iostate], iostate
     using iostate = T2;
     static constexpr iostate badbit = unspecified;
     static constexpr iostate eofbit = unspecified;
     static constexpr iostate failbit = unspecified;
     static constexpr iostate goodbit = see below;
+    // [ios.openmode], openmode
     using openmode = T3;
     static constexpr openmode app = unspecified;
     static constexpr openmode ate = unspecified;
     static constexpr openmode binary = unspecified;
     static constexpr openmode in = unspecified;
     static constexpr openmode out = unspecified;
     static constexpr openmode trunc = unspecified;
+    // [ios.seekdir], seekdir
     using seekdir = T4;
     static constexpr seekdir beg = unspecified;
     static constexpr seekdir cur = unspecified;
     static constexpr seekdir end = unspecified;
     locale imbue(const locale& loc);
     locale getloc() const;
     // [ios.base.storage], storage
     static int xalloc();
+    long&  iword(int idx);
+    void*& pword(int idx);
+    // destructor
     virtual ~ios_base();
+    // [ios.base.callback], callbacks
     enum event { erase_event, imbue_event, copyfmt_event };
+    using event_callback = void (*)(event, ios_base&, int idx);
+    void register_callback(event_callback fn, int idx);
     ios_base(const ios_base&) = delete;
     ios_base& operator=(const ios_base&) = delete;
     static bool sync_with_stdio(bool sync = true);
 — *end note*]
 #### Types <a id="ios.types">[[ios.types]]</a>
+##### Class `ios_base::failure` <a id="ios.failure">[[ios.failure]]</a>
 ``` cpp
 namespace std {
   class ios_base::failure : public system_error {
   public:
 An implementation is permitted to define `ios_base::failure` as a
 synonym for a class with equivalent functionality to class
 `ios_base::failure` shown in this subclause.
+[*Note 1*: When `ios_base::failure` is a synonym for another type, that
+type is required to provide a nested type `failure` to emulate the
+injected-class-name. — *end note*]
 The class `failure` defines the base class for the types of all objects
 thrown as exceptions, by functions in the iostreams library, to report
 errors detected during stream buffer operations.
 ``` cpp
 explicit failure(const string& msg, const error_code& ec = io_errc::stream);
 ```
+*Effects:* Constructs the base class with `msg` and `ec`.
 ``` cpp
 explicit failure(const char* msg, const error_code& ec = io_errc::stream);
 ```
+*Effects:* Constructs the base class with `msg` and `ec`.
+##### Type `ios_base::fmtflags` <a id="ios.fmtflags">[[ios.fmtflags]]</a>
 ``` cpp
 using fmtflags = T1;
 ```
+The type `fmtflags` is a bitmask type [[bitmask.types]]. Setting its
+elements has the effects indicated in [[ios.fmtflags]].
+**Table: `fmtflags` effects** <a id="ios.fmtflags">[ios.fmtflags]</a>
 | Element      | Effect(s) if set                                                                                                                        |
 | ------------ | --------------------------------------------------------------------------------------------------------------------------------------- |
 | `boolalpha`  | insert and extract `bool` type in alphabetic format                                                                                     |
 | `dec`        | converts integer input or generates integer output in decimal base                                                                      |
 | `unitbuf`    | flushes output after each output operation                                                                                              |
 | `uppercase`  | replaces certain lowercase letters with their uppercase equivalents in generated output                                                 |
 Type `fmtflags` also defines the constants indicated in
+[[ios.fmtflags.const]].
+**Table: `fmtflags` constants** <a id="ios.fmtflags.const">[ios.fmtflags.const]</a>
 | Constant      | Allowable values          |
 | ------------- | ------------------------- |
 | `adjustfield` | `left | right | internal` |
 | `basefield`   | `dec | oct | hex`         |
 | `floatfield`  | `scientific | fixed`      |
+##### Type `ios_base::iostate` <a id="ios.iostate">[[ios.iostate]]</a>
 ``` cpp
 using iostate = T2;
 ```
+The type `iostate` is a bitmask type [[bitmask.types]] that contains the
+elements indicated in [[ios.iostate]].
+**Table: `iostate` effects** <a id="ios.iostate">[ios.iostate]</a>
 | Element   | Effect(s) if set                                                                                                                                 |
 | --------- | ------------------------------------------------------------------------------------------------------------------------------------------------ |
 | `badbit`  | indicates a loss of integrity in an input or output sequence (such as an irrecoverable read error from a file);                                  |
 | `eofbit`  | indicates that an input operation reached the end of an input sequence;                                                                          |
 Type `iostate` also defines the constant:
 - `goodbit`, the value zero.
+##### Type `ios_base::openmode` <a id="ios.openmode">[[ios.openmode]]</a>
 ``` cpp
 using openmode = T3;
 ```
+The type `openmode` is a bitmask type [[bitmask.types]]. It contains the
+elements indicated in [[ios.openmode]].
+**Table: `openmode` effects** <a id="ios.openmode">[ios.openmode]</a>
 | Element  | Effect(s) if set                                                  |
 | -------- | ----------------------------------------------------------------- |
 | `app`    | seek to end before each write                                     |
 | `ate`    | open and seek to end immediately after opening                    |
 | `in`     | open for input                                                    |
 | `out`    | open for output                                                   |
 | `trunc`  | truncate an existing stream when opening                          |
+##### Type `ios_base::seekdir` <a id="ios.seekdir">[[ios.seekdir]]</a>
 ``` cpp
 using seekdir = T4;
 ```
+The type `seekdir` is an enumerated type [[enumerated.types]] that
+contains the elements indicated in [[ios.seekdir]].
+**Table: `seekdir` effects** <a id="ios.seekdir">[ios.seekdir]</a>
 | Element | Meaning                                                                                 |
 | ------- | --------------------------------------------------------------------------------------- |
 | `beg`   | request a seek (for subsequent input or output) relative to the beginning of the stream |
 | `cur`   | request a seek relative to the current position within the sequence                     |
 | `end`   | request a seek relative to the current end of the sequence                              |
+##### Class `ios_base::Init` <a id="ios.init">[[ios.init]]</a>
 ``` cpp
 namespace std {
   class ios_base::Init {
   public:
     Init();
+    Init(const Init&) = default;
     ~Init();
+    Init& operator=(const Init&) = default;
   private:
     static int init_cnt;        // exposition only
   };
 }
 ```
 The class `Init` describes an object whose construction ensures the
+construction of the eight objects declared in `<iostream>`
+[[iostream.objects]] that associate file stream buffers with the
+standard C streams provided for by the functions declared in `<cstdio>`.
 For the sake of exposition, the maintained data is presented here as:
 - `static int init_cnt`, counts the number of constructor and destructor
   calls for class `Init`, initialized to zero.
 ``` cpp
 Init();
 ```
+*Effects:* Constructs and initializes the objects `cin`, `cout`, `cerr`,
+`clog`, `wcin`, `wcout`, `wcerr`, and `wclog` if they have not already
+been constructed and initialized.
 ``` cpp
 ~Init();
 ```
+*Effects:* If there are no other instances of the class still in
+existence, calls `cout.flush()`, `cerr.flush()`, `clog.flush()`,
+`wcout.flush()`, `wcerr.flush()`, `wclog.flush()`.
+#### State functions <a id="fmtflags.state">[[fmtflags.state]]</a>
 ``` cpp
 fmtflags flags() const;
 ```
 ``` cpp
 fmtflags flags(fmtflags fmtfl);
 ```
+*Ensures:* `fmtfl == flags()`.
 *Returns:* The previous value of `flags()`.
 ``` cpp
 fmtflags setf(fmtflags fmtfl);
 ``` cpp
 streamsize precision(streamsize prec);
 ```
+*Ensures:* `prec == precision()`.
 *Returns:* The previous value of `precision()`.
 ``` cpp
 streamsize width() const;
 ``` cpp
 streamsize width(streamsize wide);
 ```
+*Ensures:* `wide == width()`.
 *Returns:* The previous value of `width()`.
+#### Functions <a id="ios.base.locales">[[ios.base.locales]]</a>
 ``` cpp
 locale imbue(const locale& loc);
 ```
+*Effects:* Calls each registered callback pair `(fn, idx)`
+[[ios.base.callback]] as `(*fn)(imbue_event, *this, idx)` at such a time
+that a call to `ios_base::getloc()` from within `fn` returns the new
+locale value `loc`.
+*Ensures:* `loc == getloc()`.
 *Returns:* The previous value of `getloc()`.
 ``` cpp
 locale getloc() const;
 ```
+*Returns:* If no locale has been imbued, a copy of the global C++
+locale, `locale()`, in effect at the time of construction. Otherwise,
+returns the imbued locale, to be used to perform locale-dependent input
+and output operations.
+#### Static members <a id="ios.members.static">[[ios.members.static]]</a>
 ``` cpp
+static bool sync_with_stdio(bool sync = true);
 ```
 *Returns:* `true` if the previous state of the standard iostream
+objects [[iostream.objects]] was synchronized and otherwise returns
 `false`. The first time it is called, the function returns `true`.
 *Effects:* If any input or output operation has occurred using the
 standard streams prior to the call, the effect is
 *implementation-defined*. Otherwise, called with a `false` argument, it
 str.rdbuf()->sputbackc(c);
 ```
 for any sequence of characters.[^6]
+#### Storage functions <a id="ios.base.storage">[[ios.base.storage]]</a>
 ``` cpp
 static int xalloc();
 ```
 *Returns:* `index` `++`.
+*Remarks:* Concurrent access to this function by multiple threads does
+not result in a data race [[intro.multithread]].
 ``` cpp
 long& iword(int idx);
 ```
+*Preconditions:* `idx` is a value obtained by a call to `xalloc`.
 *Effects:* If `iarray` is a null pointer, allocates an array of `long`
 of unspecified size and stores a pointer to its first element in
 `iarray`. The function then extends the array pointed at by `iarray` as
 necessary to include the element `iarray[idx]`. Each newly allocated
 element of the array is initialized to zero. The reference returned is
 ``` cpp
 void*& pword(int idx);
 ```
+*Preconditions:* `idx` is a value obtained by a call to `xalloc`.
 *Effects:* If `parray` is a null pointer, allocates an array of pointers
 to `void` of unspecified size and stores a pointer to its first element
 in `parray`. The function then extends the array pointed at by `parray`
 as necessary to include the element `parray[idx]`. Each newly allocated
 element of the array is initialized to a null pointer. The reference
 initialized to 0.
 *Remarks:* After a subsequent call to `pword(int)` for the same object,
 the earlier return value may no longer be valid.
+#### Callbacks <a id="ios.base.callback">[[ios.base.callback]]</a>
 ``` cpp
+void register_callback(event_callback fn, int idx);
 ```
+*Preconditions:* The function `fn` does not throw exceptions.
+*Effects:* Registers the pair `(fn, idx)` such that during calls to
+`imbue()` [[ios.base.locales]], `copyfmt()`, or `~ios_base()`
+[[ios.base.cons]], the function `fn` is called with argument `idx`.
+Functions registered are called when an event occurs, in opposite order
+of registration. Functions registered while a callback function is
+active are not called until the next event.
 *Remarks:* Identical pairs are not merged. A function registered twice
 will be called twice.
+#### Constructors and destructor <a id="ios.base.cons">[[ios.base.cons]]</a>
 ``` cpp
 ios_base();
 ```
 ``` cpp
 ~ios_base();
 ```
+*Effects:* Calls each registered callback pair `(fn, idx)`
+[[ios.base.callback]] as `(*fn)(erase_event, *this, idx)` at such time
+that any `ios_base` member function called from within `fn` has
+well-defined results.
 ### Class template `fpos` <a id="fpos">[[fpos]]</a>
 ``` cpp
 namespace std {
     stateT st;                  // exposition only
   };
 }
 ```
+#### Members <a id="fpos.members">[[fpos.members]]</a>
 ``` cpp
 void state(stateT s);
 ```
 stateT state() const;
 ```
 *Returns:* Current value of `st`.
+#### Requirements <a id="fpos.operations">[[fpos.operations]]</a>
+An `fpos` type specifies file position information. It holds a state
+object whose type is equal to the template parameter `stateT`. Type
+`stateT` shall meet the *Cpp17DefaultConstructible* (
+[[cpp17.defaultconstructible]]), *Cpp17CopyConstructible* (
+[[cpp17.copyconstructible]]), *Cpp17CopyAssignable* (
+[[cpp17.copyassignable]]), and *Cpp17Destructible* (
+[[cpp17.destructible]]) requirements. If
+`is_trivially_copy_constructible_v<stateT>` is `true`, then
+`fpos<stateT>` has a trivial copy constructor. If
+`is_trivially_copy_assignable<stateT>` is `true`, then `fpos<stateT>`
+has a trivial copy assignment operator. If
+`is_trivially_destructible_v<stateT>` is `true`, then `fpos<stateT>` has
+a trivial destructor. All specializations of `fpos` meet the
+*Cpp17DefaultConstructible*, *Cpp17CopyConstructible*,
+*Cpp17CopyAssignable*, *Cpp17Destructible*, and
+*Cpp17EqualityComparable* ([[cpp17.equalitycomparable]]) requirements.
+In addition, the expressions shown in [[fpos.operations]] are valid and
+have the indicated semantics. In that table,
 - `P` refers to an instance of `fpos`,
+- `p` and `q` refer to values of type `P` or `const P`,
+- `pl` and `ql` refer to modifiable lvalues of type `P`,
+- `O` refers to type `streamoff`, and
+- `o` refers to a value of type `streamoff` or `const streamoff`.
 Stream operations that return a value of type `traits::pos_type` return
 `P(O(-1))` as an invalid value to signal an error. If this value is used
 as an argument to any `istream`, `ostream`, or `streambuf` member that
 accepts a value of type `traits::pos_type` then the behavior of that
   };
 }
 ```
+#### Constructors <a id="basic.ios.cons">[[basic.ios.cons]]</a>
 ``` cpp
 explicit basic_ios(basic_streambuf<charT, traits>* sb);
 ```
+*Effects:* Assigns initial values to its member objects by calling
+`init(sb)`.
 ``` cpp
 basic_ios();
 ```
+*Effects:* Leaves its member objects uninitialized. The object shall be
+initialized by calling `basic_ios::init` before its first use or before
+it is destroyed, whichever comes first; otherwise the behavior is
+undefined.
 ``` cpp
 ~basic_ios();
 ```
 ``` cpp
 void init(basic_streambuf<charT, traits>* sb);
 ```
+*Ensures:* The postconditions of this function are indicated in
+[[basic.ios.cons]].
+**Table: `basic_ios::init()` effects** <a id="basic.ios.cons">[basic.ios.cons]</a>
 | Element        | Value                                                        |
 | -------------- | ------------------------------------------------------------ |
 | `rdbuf()`      | `sb`                                                         |
 | `tie()`        | `0`                                                          |
 ``` cpp
 basic_ostream<charT, traits>* tie(basic_ostream<charT, traits>* tiestr);
 ```
+*Preconditions:* If `tiestr` is not null, `tiestr` is not reachable by
 traversing the linked list of tied stream objects starting from
 `tiestr->tie()`.
+*Ensures:* `tiestr == tie()`.
 *Returns:* The previous value of `tie()`.
 ``` cpp
 basic_streambuf<charT, traits>* rdbuf() const;
 ``` cpp
 basic_streambuf<charT, traits>* rdbuf(basic_streambuf<charT, traits>* sb);
 ```
 *Effects:* Calls `clear()`.
+*Ensures:* `sb == rdbuf()`.
 *Returns:* The previous value of `rdbuf()`.
 ``` cpp
 locale imbue(const locale& loc);
 ```
+*Effects:* Calls `ios_base::imbue(loc)` [[ios.base.locales]] and if
+`rdbuf() != 0` then `rdbuf()->pubimbue(loc)` [[streambuf.locales]].
 *Returns:* The prior value of `ios_base::imbue()`.
 ``` cpp
 char narrow(char_type c, char dfault) const;
 ``` cpp
 char_type fill(char_type fillch);
 ```
+*Ensures:* `traits::eq(fillch, fill())`.
 *Returns:* The previous value of `fill()`.
 ``` cpp
 basic_ios& copyfmt(const basic_ios& rhs);
 ```
+*Effects:* If `(this == addressof(rhs))` is `true` does nothing.
+Otherwise assigns to the member objects of `*this` the corresponding
+member objects of `rhs` as follows:
+- calls each registered callback pair `(fn, idx)` as
+ `(*fn)(erase_event, *this, idx)`;
+- then, assigns to the member objects of `*this` the corresponding
+  member objects of `rhs`, except that
   - `rdstate()`, `rdbuf()`, and `exceptions()` are left unchanged;
+ - the contents of arrays pointed at by `pword` and `iword` are copied,
+ not the pointers themselves;[^10] and
   - if any newly stored pointer values in `*this` point at objects
+ stored outside the object `rhs` and those objects are destroyed when
+ `rhs` is destroyed, the newly stored pointer values are altered to
+ point at newly constructed copies of the objects;
+- then, calls each callback pair that was copied from `rhs` as
+ `(*fn)(copyfmt_event, *this, idx)`;
+- then, calls `exceptions(rhs.exceptions())`.
 [*Note 1*: The second pass through the callback pairs permits a copied
 `pword` value to be zeroed, or to have its referent deep copied or
 reference counted, or to have other special action taken. — *end note*]
+*Ensures:* The postconditions of this function are indicated in
+[[basic.ios.copyfmt]].
+**Table: `basic_ios::copyfmt()` effects** <a id="basic.ios.copyfmt">[basic.ios.copyfmt]</a>
 | Element        | Value              |
 | -------------- | ------------------ |
 | `rdbuf()`      | unchanged          |
 | `tie()`        | `rhs.tie()`        |
 ``` cpp
 void move(basic_ios& rhs);
 void move(basic_ios&& rhs);
 ```
+*Ensures:* `*this` has the state that `rhs` had before the function
+call, except that `rdbuf()` returns `nullptr`. `rhs` is in a valid but
+unspecified state, except that `rhs.rdbuf()` returns the same value as
+it returned before the function call, and `rhs.tie()` returns `nullptr`.
 ``` cpp
 void swap(basic_ios& rhs) noexcept;
 ```
+*Effects:* The states of `*this` and `rhs` are exchanged, except that
+`rdbuf()` returns the same value as it returned before the function
+call, and `rhs.rdbuf()` returns the same value as it returned before the
+function call.
 ``` cpp
 void set_rdbuf(basic_streambuf<charT, traits>* sb);
 ```
+*Preconditions:* `sb != nullptr` is `true`.
 *Effects:* Associates the `basic_streambuf` object pointed to by `sb`
 with this stream without calling `clear()`.
+*Ensures:* `rdbuf() == sb` is `true`.
 *Throws:* Nothing.
+#### Flags functions <a id="iostate.flags">[[iostate.flags]]</a>
 ``` cpp
 explicit operator bool() const;
 ```
 ``` cpp
 void clear(iostate state = goodbit);
 ```
+*Ensures:* If `rdbuf() != 0` then `state == rdstate()`; otherwise
 `rdstate() == (state | ios_base::badbit)`.
 *Effects:* If
 `((state | (rdbuf() ? goodbit : badbit)) & exceptions()) == 0`, returns.
+Otherwise, the function throws an object of class `ios_base::failure`
+[[ios.failure]], constructed with *implementation-defined* argument
+values.
 ``` cpp
 void setstate(iostate state);
 ```
 *Effects:* Calls `clear(rdstate() | state)` (which may throw
+`ios_base::failure` [[ios.failure]]).
 ``` cpp
 bool good() const;
 ```
 ``` cpp
 void exceptions(iostate except);
 ```
+*Ensures:* `except == exceptions()`.
 *Effects:* Calls `clear(rdstate())`.
 ### `ios_base` manipulators <a id="std.ios.manip">[[std.ios.manip]]</a>
 #### `fmtflags` manipulators <a id="fmtflags.manip">[[fmtflags.manip]]</a>
+Each function specified in this subclause is a designated addressable
+function [[namespace.std]].
 ``` cpp
 ios_base& boolalpha(ios_base& str);
 ```
 *Effects:* Calls `str.setf(ios_base::boolalpha)`.
 *Returns:* `str`.
 #### `adjustfield` manipulators <a id="adjustfield.manip">[[adjustfield.manip]]</a>
+Each function specified in this subclause is a designated addressable
+function [[namespace.std]].
 ``` cpp
 ios_base& internal(ios_base& str);
 ```
 *Effects:* Calls `str.setf(ios_base::internal, ios_base::adjustfield)`.
 *Returns:* `str`.
 #### `basefield` manipulators <a id="basefield.manip">[[basefield.manip]]</a>
+Each function specified in this subclause is a designated addressable
+function [[namespace.std]].
 ``` cpp
 ios_base& dec(ios_base& str);
 ```
 *Effects:* Calls `str.setf(ios_base::dec, ios_base::basefield)`.
 *Returns:* `str`.
 #### `floatfield` manipulators <a id="floatfield.manip">[[floatfield.manip]]</a>
+Each function specified in this subclause is a designated addressable
+function [[namespace.std]].
 ``` cpp
 ios_base& fixed(ios_base& str);
 ```
 *Effects:* Calls `str.setf(ios_base::fixed, ios_base::floatfield)`.
 *Returns:* `str`.
 [*Note 1*: The more obvious use of `ios_base::hex` to specify
 hexadecimal floating-point format would change the meaning of existing
+well-defined programs. C++03 gives no meaning to the combination of
 `fixed` and `scientific`. — *end note*]
 ``` cpp
 ios_base& defaultfloat(ios_base& str);
 ```
 *Effects:* Calls `str.unsetf(ios_base::floatfield)`.
 *Returns:* `str`.
+### Error reporting <a id="error.reporting">[[error.reporting]]</a>
 ``` cpp
 error_code make_error_code(io_errc e) noexcept;
 ```
     pos_type pubseekpos(pos_type sp,
                         ios_base::openmode which
                           = ios_base::in | ios_base::out);
     int      pubsync();
+    // get and put areas
     // [streambuf.pub.get], get area
     streamsize in_avail();
     int_type snextc();
     int_type sbumpc();
     int_type sgetc();
 *character sequences*:
 - a character *input sequence*;
 - a character *output sequence*.
+#### Constructors <a id="streambuf.cons">[[streambuf.cons]]</a>
 ``` cpp
 basic_streambuf();
 ```
+*Effects:* Initializes:[^13]
+- all pointer member objects to null pointers,
 - the `getloc()` member to a copy the global locale, `locale()`, at the
   time of construction.
 *Remarks:* Once the `getloc()` member is initialized, results of calling
 locale member functions, and of members of facets so obtained, can
 ``` cpp
 basic_streambuf(const basic_streambuf& rhs);
 ```
+*Ensures:*
 - `eback() == rhs.eback()`
 - `gptr() == rhs.gptr()`
 - `egptr() == rhs.egptr()`
 - `pbase() == rhs.pbase()`
 ~basic_streambuf();
 ```
 *Effects:* None.
+#### Public member functions <a id="streambuf.members">[[streambuf.members]]</a>
 ##### Locales <a id="streambuf.locales">[[streambuf.locales]]</a>
 ``` cpp
 locale pubimbue(const locale& loc);
 ```
 *Effects:* Calls `imbue(loc)`.
+*Ensures:* `loc == getloc()`.
 *Returns:* Previous value of `getloc()`.
 ``` cpp
 locale getloc() const;
 ```
 ``` cpp
 streamsize in_avail();
 ```
 *Returns:* If a read position is available, returns `egptr() - gptr()`.
+Otherwise returns `showmanyc()` [[streambuf.virt.get]].
 ``` cpp
 int_type snextc();
 ```
 ``` cpp
 int_type sbumpc();
 ```
+*Effects:* If the input sequence read position is not available, returns
 `uflow()`. Otherwise, returns `traits::to_int_type(*gptr())` and
 increments the next pointer for the input sequence.
 ``` cpp
 int_type sgetc();
 ``` cpp
 int_type sputbackc(char_type c);
 ```
+*Effects:* If the input sequence putback position is not available, or
 if `traits::eq(c, gptr()[-1])` is `false`, returns
 `pbackfail(traits::to_int_type(c))`. Otherwise, decrements the next
 pointer for the input sequence and returns
 `traits::to_int_type(*gptr())`.
 ``` cpp
 int_type sungetc();
 ```
+*Effects:* If the input sequence putback position is not available,
 returns `pbackfail()`. Otherwise, decrements the next pointer for the
 input sequence and returns `traits::to_int_type(*gptr())`.
 ##### Put area <a id="streambuf.pub.put">[[streambuf.pub.put]]</a>
 ``` cpp
 int_type sputc(char_type c);
 ```
+*Effects:* If the output sequence write position is not available,
 returns `overflow(traits::to_int_type(c))`. Otherwise, stores `c` at the
 next pointer for the output sequence, increments the pointer, and
 returns `traits::to_int_type(c)`.
 ``` cpp
 streamsize sputn(const char_type* s, streamsize n);
 ```
 *Returns:* `xsputn(s, n)`.
+#### Protected member functions <a id="streambuf.protected">[[streambuf.protected]]</a>
 ##### Assignment <a id="streambuf.assign">[[streambuf.assign]]</a>
 ``` cpp
 basic_streambuf& operator=(const basic_streambuf& rhs);
 ```
+*Ensures:*
 - `eback() == rhs.eback()`
 - `gptr() == rhs.gptr()`
 - `egptr() == rhs.egptr()`
 - `pbase() == rhs.pbase()`
 ``` cpp
 void setg(char_type* gbeg, char_type* gnext, char_type* gend);
 ```
+*Ensures:* `gbeg == eback()`, `gnext == gptr()`, and `gend == egptr()`
+are all `true`.
 ##### Put area access <a id="streambuf.put.area">[[streambuf.put.area]]</a>
 ``` cpp
 char_type* pbase() const;
 ``` cpp
 void setp(char_type* pbeg, char_type* pend);
 ```
+*Ensures:* `pbeg == pbase()`, `pbeg == pptr()`, and `pend == epptr()`
+are all `true`.
+#### Virtual functions <a id="streambuf.virtuals">[[streambuf.virtuals]]</a>
 ##### Locales <a id="streambuf.virt.locales">[[streambuf.virt.locales]]</a>
 ``` cpp
 void imbue(const locale&);
 is, if `pbase()` is non-null the characters between `pbase()` and
 `pptr()` are written to the controlled sequence. The pointers may then
 be reset as appropriate.
 *Returns:* `-1` on failure. What constitutes failure is determined by
+each derived class [[filebuf.virtuals]].
 *Default behavior:* Returns zero.
 ##### Get area <a id="streambuf.virt.get">[[streambuf.virt.get]]</a>
 ``` cpp
 int_type underflow();
 ```
 *Remarks:* The public members of `basic_streambuf` call this virtual
+function only if `gptr()` is null or `gptr() >= egptr()`.
 *Returns:* `traits::to_int_type(c)`, where `c` is the first *character*
 of the *pending sequence*, without moving the input sequence position
 past it. If the pending sequence is null then the function returns
 `traits::eof()` to indicate failure.
 ``` cpp
 int_type uflow();
 ```
+*Preconditions:* The constraints are the same as for `underflow()`,
+except that the result character is transferred from the pending
+sequence to the backup sequence, and the pending sequence is not empty
 before the transfer.
 *Default behavior:* Calls `underflow()`. If `underflow()` returns
 `traits::eof()`, returns `traits::eof()`. Otherwise, returns the value
 of `traits::to_int_type(*gptr())` and increment the value of the next
   is determined.
 - If `traits::eq_int_type(c, traits::eof())` returns `false`, then `c`
   is prepended. Whether the input sequence is backed up or modified in
   any other way is unspecified.
+*Ensures:* On return, the constraints of `gptr()`, `eback()`, and
 `pptr()` are the same as for `underflow()`.
 *Returns:* `traits::eof()` to indicate failure. Failure may occur
 because the input sequence could not be backed up, or if for some other
 reason the pointers could not be set consistent with the constraints.
 *Effects:* Consumes some initial subsequence of the characters of the
 *pending sequence*. The pending sequence is defined as the concatenation
 of
+- the empty sequence if `pbase()` is null, otherwise the
   `pptr() - pbase()` characters beginning at `pbase()`, followed by
 - the empty sequence if `traits::eq_int_type(c, traits::eof())` returns
   `true`, otherwise the sequence consisting of `c`.
 *Remarks:* The member functions `sputc()` and `sputn()` call this
 function in case that no room can be found in the put buffer enough to
 accommodate the argument character sequence.
+*Preconditions:* Every overriding definition of this virtual function
+obeys the following constraints:
+- The effect of consuming a character on the associated output sequence
+ is specified.[^16]
+- Let `r` be the number of characters in the pending sequence not
+ consumed. If `r` is nonzero then `pbase()` and `pptr()` are set so
+ that: `pptr() - pbase() == r` and the `r` characters starting at
   `pbase()` are the associated output stream. In case `r` is zero (all
   characters of the pending sequence have been consumed) then either
+ `pbase()` is set to `nullptr`, or `pbase()` and `pptr()` are both set
+ to the same non-null value.
+- The function may fail if either appending some character to the
   associated output stream fails or if it is unable to establish
   `pbase()` and `pptr()` according to the above rules.
 *Returns:* `traits::eof()` or throws an exception if the function fails.
   template<class charT, class traits>
     basic_ostream<charT, traits>& ends(basic_ostream<charT, traits>& os);
   template<class charT, class traits>
     basic_ostream<charT, traits>& flush(basic_ostream<charT, traits>& os);
+  template<class charT, class traits>
+    basic_ostream<charT, traits>& emit_on_flush(basic_ostream<charT, traits>& os);
+  template<class charT, class traits>
+    basic_ostream<charT, traits>& noemit_on_flush(basic_ostream<charT, traits>& os);
+  template<class charT, class traits>
+    basic_ostream<charT, traits>& flush_emit(basic_ostream<charT, traits>& os);
   template<class charT, class traits, class T>
     basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>&& os, const T& x);
 }
 ```
 namespace std {
   // types T1, T2, ... are unspecified implementation types
   T1 resetiosflags(ios_base::fmtflags mask);
   T2 setiosflags  (ios_base::fmtflags mask);
   T3 setbase(int base);
+  template<class charT> T4 setfill(charT c);
   T5 setprecision(int n);
   T6 setw(int n);
   template<class moneyT> T7 get_money(moneyT& mon, bool intl = false);
   template<class moneyT> T8 put_money(const moneyT& mon, bool intl = false);
   template<class charT> T9 get_time(struct tm* tmb, const charT* fmt);
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
   class basic_istream : virtual public basic_ios<charT, traits> {
   public:
+    // types (inherited from basic_ios[ios])
     using char_type   = charT;
     using int_type    = typename traits::int_type;
     using pos_type    = typename traits::pos_type;
     using off_type    = typename traits::off_type;
     using traits_type = traits;
     // [istream.cons], constructor/destructor
     explicit basic_istream(basic_streambuf<charT, traits>* sb);
     virtual ~basic_istream();
+    // [istream.sentry], prefix/suffix
     class sentry;
     // [istream.formatted], formatted input
     basic_istream<charT, traits>&
       operator>>(basic_istream<charT, traits>& (*pf)(basic_istream<charT, traits>&));
     basic_istream<charT, traits>& seekg(pos_type);
     basic_istream<charT, traits>& seekg(off_type, ios_base::seekdir);
   protected:
     // [istream.cons], copy/move constructor
+    basic_istream(const basic_istream&) = delete;
     basic_istream(basic_istream&& rhs);
     // [istream.assign], assign and swap
+    basic_istream& operator=(const basic_istream&) = delete;
     basic_istream& operator=(basic_istream&& rhs);
     void swap(basic_istream& rhs);
   };
   // [istream.extractors], character extraction templates
   template<class traits>
     basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, unsigned char&);
   template<class traits>
     basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, signed char&);
+  template<class charT, class traits, size_t N>
+    basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>&, charT(&)[N]);
+  template<class traits, size_t N>
+    basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, unsigned char(&)[N]);
+  template<class traits, size_t N>
+    basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, signed char(&)[N]);
 }
 ```
 The class template `basic_istream` defines a number of member function
 signatures that assist in reading and interpreting input from sequences
 or `rdbuf()->sgetc()`. They may use other public members of `istream`.
 If `rdbuf()->sbumpc()` or `rdbuf()->sgetc()` returns `traits::eof()`,
 then the input function, except as explicitly noted otherwise, completes
 its actions and does `setstate(eofbit)`, which may throw
+`ios_base::failure` [[iostate.flags]], before returning.
 If one of these called functions throws an exception, then unless
+explicitly noted otherwise, the input function sets `badbit` in the
+error state. If `badbit` is set in `exceptions()`, the input function
+rethrows the exception without completing its actions, otherwise it does
+not throw anything and proceeds as if the called function had returned a
 failure indication.
+##### Constructors <a id="istream.cons">[[istream.cons]]</a>
 ``` cpp
 explicit basic_istream(basic_streambuf<charT, traits>* sb);
 ```
+*Effects:* Initializes the base class subobject with
+`basic_ios::init(sb)` [[basic.ios.cons]].
+*Ensures:* `gcount() == 0`.
 ``` cpp
 basic_istream(basic_istream&& rhs);
 ```
+*Effects:* Default constructs the base class, copies the `gcount()` from
+`rhs`, calls `basic_ios<charT, traits>::move(rhs)` to initialize the
+base class, and sets the `gcount()` for `rhs` to 0.
 ``` cpp
 virtual ~basic_istream();
 ```
 *Remarks:* Does not perform any operations of `rdbuf()`.
+##### Assignment and swap <a id="istream.assign">[[istream.assign]]</a>
 ``` cpp
 basic_istream& operator=(basic_istream&& rhs);
 ```
+*Effects:* Equivalent to: `swap(rhs)`.
 *Returns:* `*this`.
 ``` cpp
 void swap(basic_istream& rhs);
 ```
 *Effects:* Calls `basic_ios<charT, traits>::swap(rhs)`. Exchanges the
 values returned by `gcount()` and `rhs.gcount()`.
+##### Class `basic_istream::sentry` <a id="istream.sentry">[[istream.sentry]]</a>
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
   class basic_istream<charT, traits>::sentry {
     bool ok_;                   // exposition only
   public:
     explicit sentry(basic_istream<charT, traits>& is, bool noskipws = false);
     ~sentry();
     explicit operator bool() const { return ok_; }
 ```
 If, after any preparation is completed, `is.good()` is `true`,
 `ok_ != false` otherwise, `ok_ == false`. During preparation, the
 constructor may call `setstate(failbit)` (which may throw
+`ios_base::failure` [[iostate.flags]]).[^19]
 ``` cpp
 ~sentry();
 ```
 ``` cpp
 explicit operator bool() const;
 ```
+*Returns:* `ok_`.
 #### Formatted input functions <a id="istream.formatted">[[istream.formatted]]</a>
 ##### Common requirements <a id="istream.formatted.reqmts">[[istream.formatted.reqmts]]</a>
 Each formatted input function begins execution by constructing an object
 of class `sentry` with the `noskipws` (second) argument `false`. If the
 `sentry` object returns `true`, when converted to a value of type
 `bool`, the function endeavors to obtain the requested input. If an
+exception is thrown during input then `ios_base::badbit` is turned
+on[^20] in `*this`’s error state. If `(exceptions()&badbit) != 0` then
+the exception is rethrown. In any case, the formatted input function
 destroys the `sentry` object. If no exception has been thrown, it
 returns `*this`.
 ##### Arithmetic extractors <a id="istream.formatted.arithmetic">[[istream.formatted.arithmetic]]</a>
 operator>>(bool& val);
 operator>>(void*& val);
 ```
 As in the case of the inserters, these extractors depend on the locale’s
+`num_get<>` [[locale.num.get]] object to perform parsing the input
 stream data. These extractors behave as formatted input functions (as
 described in  [[istream.formatted.reqmts]]). After a sentry object is
 constructed, the conversion occurs as if performed by the following code
 fragment:
 in  [[istream.formatted.reqmts]]).
 *Returns:* `*this`.
 ``` cpp
+template<class charT, class traits, size_t N>
+  basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>& in, charT (&s)[N]);
+template<class traits, size_t N>
+  basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, unsigned char (&s)[N]);
+template<class traits, size_t N>
+  basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, signed char (&s)[N]);
 ```
 *Effects:* Behaves like a formatted input member (as described
 in  [[istream.formatted.reqmts]]) of `in`. After a `sentry` object is
+constructed, `operator>>` extracts characters and stores them into `s`.
+If `width()` is greater than zero, `n` is `min(size_t(width()), N)`.
+Otherwise `n` is `N`. `n` is the maximum number of characters stored.
 Characters are extracted and stored until any of the following occurs:
 - `n-1` characters are stored;
 - end of file occurs on the input sequence;
 `operator>>` then stores a null byte (`charT()`) in the next position,
 which may be the first position if no characters were extracted.
 `operator>>` then calls `width(0)`.
 If the function extracted no characters, it calls `setstate(failbit)`,
+which may throw `ios_base::failure` [[iostate.flags]].
 *Returns:* `in`.
 ``` cpp
 template<class charT, class traits>
 ``` cpp
 basic_istream<charT, traits>& operator>>(basic_streambuf<charT, traits>* sb);
 ```
+*Effects:* Behaves as an unformatted input
+function [[istream.unformatted]]. If `sb` is null, calls
+`setstate(failbit)`, which may throw `ios_base::failure`
+[[iostate.flags]]. After a sentry object is constructed, extracts
+characters from `*this` and inserts them in the output sequence
+controlled by `sb`. Characters are extracted and inserted until any of
+the following occurs:
 - end-of-file occurs on the input sequence;
 - inserting in the output sequence fails (in which case the character to
   be inserted is not extracted);
 - an exception occurs (in which case the exception is caught).
 If the function inserts no characters, it calls `setstate(failbit)`,
+which may throw `ios_base::failure` [[iostate.flags]]. If it inserted no
+characters because it caught an exception thrown while extracting
+characters from `*this` and `failbit` is set in `exceptions()`
+[[iostate.flags]], then the caught exception is rethrown.
 *Returns:* `*this`.
 #### Unformatted input functions <a id="istream.unformatted">[[istream.unformatted]]</a>
 a value of type `bool`, the function returns without attempting to
 obtain any input. In either case the number of extracted characters is
 set to 0; unformatted input functions taking a character array of
 nonzero size as an argument shall also store a null character (using
 `charT()`) in the first location of the array. If an exception is thrown
+during input then `ios_base::badbit` is turned on[^23] in `*this`’s
+error state. (Exceptions thrown from `basic_ios<>::clear()` are not
+caught or rethrown.) If `(exceptions()&badbit) != 0` then the exception
+is rethrown. It also counts the number of characters extracted. If no
 exception has been thrown it ends by storing the count in a member
 object and returning the value specified. In any event the `sentry`
 object is destroyed before leaving the unformatted input function.
 ``` cpp
 ```
 *Effects:* Behaves as an unformatted input function (as described
 above). After constructing a sentry object, extracts a character `c`, if
 one is available. Otherwise, the function calls `setstate(failbit)`,
+which may throw `ios_base::failure` [[iostate.flags]].
 *Returns:* `c` if available, otherwise `traits::eof()`.
 ``` cpp
 basic_istream<charT, traits>& get(char_type& c);
 ```
 *Effects:* Behaves as an unformatted input function (as described
 above). After constructing a sentry object, extracts a character, if one
 is available, and assigns it to `c`.[^24] Otherwise, the function calls
+`setstate(failbit)` (which may throw `ios_base::failure`
+[[iostate.flags]]).
 *Returns:* `*this`.
 ``` cpp
 basic_istream<charT, traits>& get(char_type* s, streamsize n, char_type delim);
   calls `setstate(eofbit)`);
 - `traits::eq(c, delim)` for the next available input character `c` (in
   which case `c` is not extracted).
 If the function stores no characters, it calls `setstate(failbit)`
+(which may throw `ios_base::failure` [[iostate.flags]]). In any case, if
+`n` is greater than zero it then stores a null character into the next
+successive location of the array.
 *Returns:* `*this`.
 ``` cpp
 basic_istream<charT, traits>& get(char_type* s, streamsize n);
   which case `c` is not extracted);
 - an exception occurs (in which case, the exception is caught but not
   rethrown).
 If the function inserts no characters, it calls `setstate(failbit)`,
+which may throw `ios_base::failure` [[iostate.flags]].
 *Returns:* `*this`.
 ``` cpp
 basic_istream<charT, traits>& get(basic_streambuf<char_type, traits>& sb);
     the function calls `setstate(failbit)`).
 These conditions are tested in the order shown.[^28]
 If the function extracts no characters, it calls `setstate(failbit)`
+(which may throw `ios_base::failure` [[iostate.flags]]).[^29]
 In any case, if `n` is greater than zero, it then stores a null
 character (using `charT()`) into the next successive location of the
 array.
 *Effects:* Behaves as an unformatted input function (as described
 above). After constructing a sentry object, extracts characters and
 discards them. Characters are extracted until any of the following
 occurs:
+- `n != numeric_limits<streamsize>::max()` [[numeric.limits]] and `n`
   characters have been extracted so far
 - end-of-file occurs on the input sequence (in which case the function
+  calls `setstate(eofbit)`, which may throw `ios_base::failure`
+  [[iostate.flags]]);
 - `traits::eq_int_type(traits::to_int_type(c), delim)` for the next
   available input character `c` (in which case `c` is extracted).
 *Remarks:* The last condition will never occur if
 `traits::eq_int_type(delim, traits::eof())`.
 extracted and stored until either of the following occurs:
 - `n` characters are stored;
 - end-of-file occurs on the input sequence (in which case the function
   calls `setstate(failbit | eofbit)`, which may throw
+  `ios_base::failure` [[iostate.flags]]).
 *Returns:* `*this`.
 ``` cpp
 streamsize readsome(char_type* s, streamsize n);
 above). After constructing a sentry object, if `!good()` calls
 `setstate(failbit)` which may throw an exception, and return. Otherwise
 extracts characters and stores them into successive locations of an
 array whose first element is designated by `s`. If
 `rdbuf()->in_avail() == -1`, calls `setstate(eofbit)` (which may throw
+`ios_base::failure` [[iostate.flags]]), and extracts no characters;
 - If `rdbuf()->in_avail() == 0`, extracts no characters
 - If `rdbuf()->in_avail() > 0`, extracts `min(rdbuf()->in_avail(), n))`.
 *Returns:* The number of characters extracted.
 *Effects:* Behaves as an unformatted input function (as described
 above), except that the function first clears `eofbit`. After
 constructing a sentry object, if `!good()` calls `setstate(failbit)`
 which may throw an exception, and return. If `rdbuf()` is not null,
+calls `rdbuf()->sputbackc(c)`. If `rdbuf()` is null, or if `sputbackc`
 returns `traits::eof()`, calls `setstate(badbit)` (which may throw
+`ios_base::failure` [[iostate.flags]]).
 [*Note 1*: This function extracts no characters, so the value returned
 by the next call to `gcount()` is 0. — *end note*]
 *Returns:* `*this`.
 *Effects:* Behaves as an unformatted input function (as described
 above), except that the function first clears `eofbit`. After
 constructing a sentry object, if `!good()` calls `setstate(failbit)`
 which may throw an exception, and return. If `rdbuf()` is not null,
+calls `rdbuf()->sungetc()`. If `rdbuf()` is null, or if `sungetc`
 returns `traits::eof()`, calls `setstate(badbit)` (which may throw
+`ios_base::failure` [[iostate.flags]]).
 [*Note 2*: This function extracts no characters, so the value returned
 by the next call to `gcount()` is 0. — *end note*]
 *Returns:* `*this`.
 above), except that it does not count the number of characters extracted
 and does not affect the value returned by subsequent calls to
 `gcount()`. After constructing a sentry object, if `rdbuf()` is a null
 pointer, returns `-1`. Otherwise, calls `rdbuf()->pubsync()` and, if
 that function returns `-1` calls `setstate(badbit)` (which may throw
+`ios_base::failure` [[iostate.flags]], and returns `-1`. Otherwise,
 returns zero.
 ``` cpp
 pos_type tellg();
 ```
 *Returns:* `*this`.
 #### Standard `basic_istream` manipulators <a id="istream.manip">[[istream.manip]]</a>
+Each instantiation of the function template specified in this subclause
+is a designated addressable function [[namespace.std]].
 ``` cpp
 template<class charT, class traits>
   basic_istream<charT, traits>& ws(basic_istream<charT, traits>& is);
 ```
+*Effects:* Behaves as an unformatted input
+function [[istream.unformatted]], except that it does not count the
+number of characters extracted and does not affect the value returned by
+subsequent calls to `is.gcount()`. After constructing a sentry object
 extracts characters as long as the next available character `c` is
 whitespace or until there are no more characters in the sequence.
 Whitespace characters are distinguished with the same criterion as used
+by `sentry::sentry` [[istream.sentry]]. If `ws` stops extracting
 characters because there are no more available it sets `eofbit`, but not
 `failbit`.
 *Returns:* `is`.
 #### Rvalue stream extraction <a id="istream.rvalue">[[istream.rvalue]]</a>
 ``` cpp
+template<class Istream, class T>
+ Istream&& operator>>(Istream&& is, T&& x);
 ```
+*Constraints:* The expression `is >> std::forward<T>(x)` is well-formed
+when treated as an unevaluated operand and `Istream` is publicly and
+unambiguously derived from `ios_base`.
 *Effects:* Equivalent to:
 ``` cpp
 is >> std::forward<T>(x);
+return std::move(is);
 ```
 #### Class template `basic_iostream` <a id="iostreamclass">[[iostreamclass]]</a>
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
     // [iostream.dest], destructor
     virtual ~basic_iostream();
   protected:
     // [iostream.cons], constructor
+    basic_iostream(const basic_iostream&) = delete;
     basic_iostream(basic_iostream&& rhs);
     // [iostream.assign], assign and swap
+    basic_iostream& operator=(const basic_iostream&) = delete;
     basic_iostream& operator=(basic_iostream&& rhs);
     void swap(basic_iostream& rhs);
   };
 }
 ```
 The class template `basic_iostream` inherits a number of functions that
 allow reading input and writing output to sequences controlled by a
 stream buffer.
+##### Constructors <a id="iostream.cons">[[iostream.cons]]</a>
 ``` cpp
 explicit basic_iostream(basic_streambuf<charT, traits>* sb);
 ```
+*Effects:* Initializes the base class subobjects with
+`basic_istream<charT, traits>(sb)` [[istream]] and
+`basic_ostream<charT, traits>(sb)` [[ostream]].
+*Ensures:* `rdbuf() == sb` and `gcount() == 0`.
 ``` cpp
 basic_iostream(basic_iostream&& rhs);
 ```
 *Effects:* Move constructs from the rvalue `rhs` by constructing the
 `basic_istream` base class with `move(rhs)`.
+##### Destructor <a id="iostream.dest">[[iostream.dest]]</a>
 ``` cpp
 virtual ~basic_iostream();
 ```
 *Remarks:* Does not perform any operations on `rdbuf()`.
+##### Assignment and swap <a id="iostream.assign">[[iostream.assign]]</a>
 ``` cpp
 basic_iostream& operator=(basic_iostream&& rhs);
 ```
+*Effects:* Equivalent to: `swap(rhs)`.
 ``` cpp
 void swap(basic_iostream& rhs);
 ```
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
   class basic_ostream : virtual public basic_ios<charT, traits> {
   public:
+    // types (inherited from basic_ios[ios])
     using char_type   = charT;
     using int_type    = typename traits::int_type;
     using pos_type    = typename traits::pos_type;
     using off_type    = typename traits::off_type;
     using traits_type = traits;
     // [ostream.cons], constructor/destructor
     explicit basic_ostream(basic_streambuf<char_type, traits>* sb);
     virtual ~basic_ostream();
+    // [ostream.sentry], prefix/suffix
     class sentry;
     // [ostream.formatted], formatted output
     basic_ostream<charT, traits>&
       operator<<(basic_ostream<charT, traits>& (*pf)(basic_ostream<charT, traits>&));
     basic_ostream<charT, traits>& seekp(pos_type);
     basic_ostream<charT, traits>& seekp(off_type, ios_base::seekdir);
   protected:
     // [ostream.cons], copy/move constructor
+    basic_ostream(const basic_ostream&) = delete;
     basic_ostream(basic_ostream&& rhs);
     // [ostream.assign], assign and swap
+    basic_ostream& operator=(const basic_ostream&) = delete;
     basic_ostream& operator=(basic_ostream&& rhs);
     void swap(basic_ostream& rhs);
   };
   // [ostream.inserters.character], character inserters
   template<class traits>
     basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, signed char);
   template<class traits>
     basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, unsigned char);
+  template<class traits>
+    basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, wchar_t) = delete;
+  template<class traits>
+    basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, char8_t) = delete;
+  template<class traits>
+    basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, char16_t) = delete;
+  template<class traits>
+    basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, char32_t) = delete;
+  template<class traits>
+    basic_ostream<wchar_t, traits>&
+      operator<<(basic_ostream<wchar_t, traits>&, char8_t) = delete;
+  template<class traits>
+    basic_ostream<wchar_t, traits>&
+      operator<<(basic_ostream<wchar_t, traits>&, char16_t) = delete;
+  template<class traits>
+    basic_ostream<wchar_t, traits>&
+      operator<<(basic_ostream<wchar_t, traits>&, char32_t) = delete;
   template<class charT, class traits>
     basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>&, const charT*);
   template<class charT, class traits>
     basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>&, const char*);
   template<class traits>
   template<class traits>
     basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const signed char*);
   template<class traits>
     basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const unsigned char*);
+  template<class traits>
+    basic_ostream<char, traits>&
+      operator<<(basic_ostream<char, traits>&, const wchar_t*) = delete;
+  template<class traits>
+    basic_ostream<char, traits>&
+      operator<<(basic_ostream<char, traits>&, const char8_t*) = delete;
+  template<class traits>
+    basic_ostream<char, traits>&
+      operator<<(basic_ostream<char, traits>&, const char16_t*) = delete;
+  template<class traits>
+    basic_ostream<char, traits>&
+      operator<<(basic_ostream<char, traits>&, const char32_t*) = delete;
+  template<class traits>
+    basic_ostream<wchar_t, traits>&
+      operator<<(basic_ostream<wchar_t, traits>&, const char8_t*) = delete;
+  template<class traits>
+    basic_ostream<wchar_t, traits>&
+      operator<<(basic_ostream<wchar_t, traits>&, const char16_t*) = delete;
+  template<class traits>
+    basic_ostream<wchar_t, traits>&
+      operator<<(basic_ostream<wchar_t, traits>&, const char32_t*) = delete;
 }
 ```
 The class template `basic_ostream` defines a number of member function
 signatures that assist in formatting and writing output to output
 `rdbuf()->sputc(int_type)`. They may use other public members of
 `basic_ostream` except that they shall not invoke any virtual members of
 `rdbuf()` except `overflow()`, `xsputn()`, and `sync()`.
 If one of these called functions throws an exception, then unless
+explicitly noted otherwise the output function sets `badbit` in the
+error state. If `badbit` is set in `exceptions()`, the output function
+rethrows the exception without completing its actions, otherwise it does
+not throw anything and proceeds as if the called function had returned a
+failure indication.
+[*Note 1*: The deleted overloads of `operator<<` prevent formatting
+characters as integers and strings as pointers. — *end note*]
+##### Constructors <a id="ostream.cons">[[ostream.cons]]</a>
 ``` cpp
 explicit basic_ostream(basic_streambuf<charT, traits>* sb);
 ```
+*Effects:* Initializes the base class subobject with
+`basic_ios<charT, traits>::init(sb)` [[basic.ios.cons]].
+*Ensures:* `rdbuf() == sb`.
 ``` cpp
 basic_ostream(basic_ostream&& rhs);
 ```
 ``` cpp
 virtual ~basic_ostream();
 ```
 *Remarks:* Does not perform any operations on `rdbuf()`.
+##### Assignment and swap <a id="ostream.assign">[[ostream.assign]]</a>
 ``` cpp
 basic_ostream& operator=(basic_ostream&& rhs);
 ```
+*Effects:* Equivalent to: `swap(rhs)`.
 *Returns:* `*this`.
 ``` cpp
 void swap(basic_ostream& rhs);
 ```
 *Effects:* Calls `basic_ios<charT, traits>::swap(rhs)`.
+##### Class `basic_ostream::sentry` <a id="ostream.sentry">[[ostream.sentry]]</a>
 ``` cpp
 namespace std {
   template<class charT, class traits = char_traits<charT>>
   class basic_ostream<charT, traits>::sentry {
 If `os.tie()` is not a null pointer, calls `os.tie()->flush()`.[^31]
 If, after any preparation is completed, `os.good()` is `true`,
 `ok_ == true` otherwise, `ok_ == false`. During preparation, the
 constructor may call `setstate(failbit)` (which may throw
+`ios_base::failure` [[iostate.flags]]).[^32]
 ``` cpp
 ~sentry();
 ```
 explicit operator bool() const;
 ```
 *Effects:* Returns `ok_`.
+##### Seek members <a id="ostream.seeks">[[ostream.seeks]]</a>
 Each seek member function begins execution by constructing an object of
 class `sentry`. It returns by destroying the `sentry` object.
 ``` cpp
 Each formatted output function begins execution by constructing an
 object of class `sentry`. If this object returns `true` when converted
 to a value of type `bool`, the function endeavors to generate the
 requested output. If the generation fails, then the formatted output
 function does `setstate(ios_base::failbit)`, which might throw an
+exception. If an exception is thrown during output, then
+`ios_base::badbit` is turned on[^33] in `*this`’s error state. If
 `(exceptions()&badbit) != 0` then the exception is rethrown. Whether or
 not an exception is thrown, the `sentry` object is destroyed before
 leaving the formatted output function. If no exception is thrown, the
 result of the formatted output function is `*this`.
 ``` cpp
 basic_ostream<charT, traits>& operator<<(basic_streambuf<charT, traits>* sb);
 ```
+*Effects:* Behaves as an unformatted output
+function [[ostream.unformatted]]. After the sentry object is
+constructed, if `sb` is null calls `setstate(badbit)` (which may throw
 `ios_base::failure`).
 Gets characters from `sb` and inserts them in `*this`. Characters are
 read from `sb` and inserted until any of the following occurs:
 - inserting in the output sequence fails (in which case the character to
   be inserted is not extracted);
 - an exception occurs while getting a character from `sb`.
 If the function inserts no characters, it calls `setstate(failbit)`
+(which may throw `ios_base::failure` [[iostate.flags]]). If an exception
+was thrown while extracting a character, the function sets `failbit` in
+the error state, and if `failbit` is set in `exceptions()` the caught
+exception is rethrown.
 *Returns:* `*this`.
 ``` cpp
 basic_ostream<charT, traits>& operator<<(nullptr_t);
 ``` cpp
 return *this << s;
 ```
+where `s` is an *implementation-defined* NTCTS [[defns.ntcts]].
 ##### Character inserter function templates <a id="ostream.inserters.character">[[ostream.inserters.character]]</a>
 ``` cpp
 template<class charT, class traits>
 template<class traits>
   basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out, unsigned char c);
 ```
 *Effects:* Behaves as a formatted output
+function [[ostream.formatted.reqmts]] of `out`. Constructs a character
+sequence `seq`. If `c` has type `char` and the character type of the
+stream is not `char`, then `seq` consists of `out.widen(c)`; otherwise
+`seq` consists of `c`. Determines padding for `seq` as described
+in  [[ostream.formatted.reqmts]]. Inserts `seq` into `out`. Calls
+`os.width(0)`.
 *Returns:* `out`.
 ``` cpp
 template<class charT, class traits>
 template<class traits>
   basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out,
                                           const unsigned char* s);
 ```
+*Preconditions:* `s` is not a null pointer.
 *Effects:* Behaves like a formatted inserter (as described
 in  [[ostream.formatted.reqmts]]) of `out`. Creates a character sequence
 `seq` of `n` characters starting at `s`, each widened using
+`out.widen()` [[basic.ios.members]], where `n` is the number that would
+be computed as if by:
 - `traits::length(s)` for the overload where the first argument is of
   type `basic_ostream<charT, traits>&` and the second is of type
   `const charT*`, and also for the overload where the first argument is
   of type `basic_ostream<char, traits>&` and the second is of type
 Each unformatted output function begins execution by constructing an
 object of class `sentry`. If this object returns `true`, while
 converting to a value of type `bool`, the function endeavors to generate
 the requested output. If an exception is thrown during output, then
+`ios_base::badbit` is turned on[^36] in `*this`’s error state. If
 `(exceptions() & badbit) != 0` then the exception is rethrown. In any
 case, the unformatted output function ends by destroying the sentry
 object, then, if no exception was thrown, returning the value specified
 for the unformatted output function.
 *Effects:* Behaves as an unformatted output function (as described
 above). After constructing a sentry object, inserts the character `c`,
 if possible.[^37]
+Otherwise, calls `setstate(badbit)` (which may throw `ios_base::failure`
+[[iostate.flags]]).
 *Returns:* `*this`.
 ``` cpp
 basic_ostream& write(const char_type* s, streamsize n);
 by `s`.[^38] Characters are inserted until either of the following
 occurs:
 - `n` characters are inserted;
 - inserting in the output sequence fails (in which case the function
+  calls `setstate(badbit)`, which may throw `ios_base::failure`
+  [[iostate.flags]]).
 *Returns:* `*this`.
 ``` cpp
 basic_ostream& flush();
 *Effects:* Behaves as an unformatted output function (as described
 above). If `rdbuf()` is not a null pointer, constructs a sentry object.
 If this object returns `true` when converted to a value of type `bool`
 the function calls `rdbuf()->pubsync()`. If that function returns -1
+calls `setstate(badbit)` (which may throw `ios_base::failure`
+[[iostate.flags]]). Otherwise, if the sentry object returns `false`,
+does nothing.
 *Returns:* `*this`.
+#### Standard manipulators <a id="ostream.manip">[[ostream.manip]]</a>
+Each instantiation of any of the function templates specified in this
+subclause is a designated addressable function [[namespace.std]].
 ``` cpp
 template<class charT, class traits>
   basic_ostream<charT, traits>& endl(basic_ostream<charT, traits>& os);
 ```
 *Effects:* Calls `os.flush()`.
 *Returns:* `os`.
+``` cpp
+template<class charT, class traits>
+  basic_ostream<charT, traits>& emit_on_flush(basic_ostream<charT, traits>& os);
+```
+*Effects:* If `os.rdbuf()` is a
+`basic_syncbuf<charT, traits, Allocator>*`, called `buf` for the purpose
+of exposition, calls `buf->set_emit_on_sync(true)`. Otherwise this
+manipulator has no effect.
+[*Note 1*: To work around the issue that the `Allocator` template
+argument cannot be deduced, implementations can introduce an
+intermediate base class to `basic_syncbuf` that manages its
+`emit_on_sync` flag. — *end note*]
+*Returns:* `os`.
+``` cpp
+template<class charT, class traits>
+  basic_ostream<charT, traits>& noemit_on_flush(basic_ostream<charT, traits>& os);
+```
+*Effects:* If `os.rdbuf()` is a
+`basic_syncbuf<charT, traits, Allocator>*`, called `buf` for the purpose
+of exposition, calls `buf->set_emit_on_sync(false)`. Otherwise this
+manipulator has no effect.
+*Returns:* `os`.
+``` cpp
+template<class charT, class traits>
+  basic_ostream<charT, traits>& flush_emit(basic_ostream<charT, traits>& os);
+```
+*Effects:* Calls `os.flush()`. Then, if `os.rdbuf()` is a
+`basic_syncbuf<charT, traits, Allocator>*`, called `buf` for the purpose
+of exposition, calls `buf->emit()`.
+*Returns:* `os`.
 #### Rvalue stream insertion <a id="ostream.rvalue">[[ostream.rvalue]]</a>
 ``` cpp
+template<class Ostream, class T>
+ Ostream&& operator<<(Ostream&& os, const T& x);
 ```
+*Constraints:* The expression `os << x` is well-formed when treated as
+an unevaluated operand and `Ostream` is publicly and unambiguously
+derived from `ios_base`.
 *Effects:* As if by: `os << x;`
+*Returns:* `std::move(os)`.
 ### Standard manipulators <a id="std.manip">[[std.manip]]</a>
 The header `<iomanip>` defines several functions that support extractors
 and inserters that alter information maintained by class `ios_base` and
   // reset specified flags
   str.setf(ios_base::fmtflags(0), mask);
 }
 ```
+The expression `out << resetiosflags(mask)` has type
 `basic_ostream<charT, traits>&` and value `out`. The expression
+`in >> resetiosflags(mask)` has type `basic_istream<charT, traits>&` and
+value `in`.
 ``` cpp
 unspecified setiosflags(ios_base::fmtflags mask);
 ```
   // set specified flags
   str.setf(mask);
 }
 ```
+The expression `out << setiosflags(mask)` has type
 `basic_ostream<charT, traits>&` and value `out`. The expression
+`in >> setiosflags(mask)` has type `basic_istream<charT, traits>&` and
+value `in`.
 ``` cpp
 unspecified setbase(int base);
 ```
       base == 16 ? ios_base::hex :
       ios_base::fmtflags(0), ios_base::basefield);
 }
 ```
+The expression `out << setbase(base)` has type
 `basic_ostream<charT, traits>&` and value `out`. The expression
+`in >> setbase(base)` has type `basic_istream<charT, traits>&` and value
+`in`.
 ``` cpp
 unspecified setfill(char_type c);
 ```
   // set fill character
   str.fill(c);
 }
 ```
+The expression `out << setfill(c)` has type
 `basic_ostream<charT, traits>&` and value `out`.
 ``` cpp
 unspecified setprecision(int n);
 ```
   // set precision
   str.precision(n);
 }
 ```
+The expression `out << setprecision(n)` has type
 `basic_ostream<charT, traits>&` and value `out`. The expression
+`in >> setprecision(n)` has type `basic_istream<charT, traits>&` and
+value `in`.
 ``` cpp
 unspecified setw(int n);
 ```
   // set width
   str.width(n);
 }
 ```
+The expression `out << setw(n)` has type `basic_ostream<charT, traits>&`
+and value `out`. The expression `in >> setw(n)` has type
+`basic_istream<charT, traits>&` and value `in`.
 ### Extended manipulators <a id="ext.manip">[[ext.manip]]</a>
 The header `<iomanip>` defines several functions that support extractors
 and inserters that allow for the parsing and formatting of sequences and
 ``` cpp
 template<class moneyT> unspecified get_money(moneyT& mon, bool intl = false);
 ```
+*Mandates:* The type `moneyT` is either `long double` or a
+specialization of the `basic_string` template [[strings]].
 *Effects:* The expression `in >> get_money(mon, intl)` described below
+behaves as a formatted input function [[istream.formatted.reqmts]].
 *Returns:* An object of unspecified type such that if `in` is an object
 of type `basic_istream<charT, traits>` then the expression
 `in >> get_money(mon, intl)` behaves as if it called `f(in, mon, intl)`,
 where the function `f` is defined as:
   if (ios_base::goodbit != err)
     str.setstate(err);
 }
 ```
+The expression `in >> get_money(mon, intl)` has type
 `basic_istream<charT, traits>&` and value `in`.
 ``` cpp
 template<class moneyT> unspecified put_money(const moneyT& mon, bool intl = false);
 ```
+*Mandates:* The type `moneyT` is either `long double` or a
+specialization of the `basic_string` template [[strings]].
 *Returns:* An object of unspecified type such that if `out` is an object
 of type `basic_ostream<charT, traits>` then the expression
 `out << put_money(mon, intl)` behaves as a formatted output
+function [[ostream.formatted.reqmts]] that calls `f(out, mon, intl)`,
 where the function `f` is defined as:
 ``` cpp
 template<class charT, class traits, class moneyT>
 void f(basic_ios<charT, traits>& str, const moneyT& mon, bool intl) {
   const MoneyPut& mp = use_facet<MoneyPut>(str.getloc());
   const Iter end = mp.put(Iter(str.rdbuf()), intl, str, str.fill(), mon);
   if (end.failed())
+    str.setstate(ios_base::badbit);
 }
 ```
+The expression `out << put_money(mon, intl)` has type
 `basic_ostream<charT, traits>&` and value `out`.
 ``` cpp
 template<class charT> unspecified get_time(struct tm* tmb, const charT* fmt);
 ```
+*Preconditions:* The argument `tmb` is a valid pointer to an object of
+type `struct tm`, and \[`fmt`, `fmt + char_traits<charT>::length(fmt)`)
+is a valid range.
 *Returns:* An object of unspecified type such that if `in` is an object
 of type `basic_istream<charT, traits>` then the expression
 `in >> get_time(tmb, fmt)` behaves as if it called `f(in, tmb, fmt)`,
 where the function `f` is defined as:
   if (err != ios_base::goodbit)
     str.setstate(err);
 }
 ```
+The expression `in >> get_time(tmb, fmt)` has type
 `basic_istream<charT, traits>&` and value `in`.
 ``` cpp
 template<class charT> unspecified put_time(const struct tm* tmb, const charT* fmt);
 ```
+*Preconditions:* The argument `tmb` is a valid pointer to an object of
+type `struct tm`, and \[`fmt`, `fmt + char_traits<charT>::length(fmt)`)
+is a valid range.
 *Returns:* An object of unspecified type such that if `out` is an object
 of type `basic_ostream<charT, traits>` then the expression
 `out << put_time(tmb, fmt)` behaves as if it called `f(out, tmb, fmt)`,
 where the function `f` is defined as:
   if (end.failed())
     str.setstate(ios_base::badbit);
 }
 ```
+The expression `out << put_time(tmb, fmt)` has type
 `basic_ostream<charT, traits>&` and value `out`.
 ### Quoted manipulators <a id="quoted.manip">[[quoted.manip]]</a>
 [*Note 1*: Quoted manipulators provide string insertion and extraction
 *Returns:* An object of unspecified type such that if `out` is an
 instance of `basic_ostream` with member type `char_type` the same as
 `charT` and with member type `traits_type`, which in the second and
 third forms is the same as `traits`, then the expression
 `out << quoted(s, delim, escape)` behaves as a formatted output
+function [[ostream.formatted.reqmts]] of `out`. This forms a character
+sequence `seq`, initially consisting of the following elements:
 - `delim`.
 - Each character in `s`. If the character to be output is equal to
   `escape` or `delim`, as determined by `traits_type::eq`, first output
   `escape`.
 Let `x` be the number of elements initially in `seq`. Then padding is
 determined for `seq` as described in  [[ostream.formatted.reqmts]],
 `seq` is inserted as if by calling `out.rdbuf()->sputn(seq, n)`, where
 `n` is the larger of `out.width()` and `x`, and `out.width(0)` is
+called. The expression `out << quoted(s, delim, escape)` has type
 `basic_ostream<charT, traits>&` and value `out`.
 ``` cpp
 template<class charT, class traits, class Allocator>
   unspecified quoted(basic_string<charT, traits, Allocator>& s,
 - If `in` is an instance of `basic_istream` with member types
   `char_type` and `traits_type` the same as `charT` and `traits`,
   respectively, then the expression `in >> quoted(s, delim, escape)`
   behaves as if it extracts the following characters from `in` using
+  `operator>>(basic_istream<charT, traits>&, charT&)`
+ [[istream.extractors]] which may throw `ios_base::failure`
+  [[ios.failure]]:
   - If the first character extracted is equal to `delim`, as determined
     by `traits_type::eq`, then:
     - Turn off the `skipws` flag.
     - `s.clear()`
     - Until an unescaped `delim` character is reached or `!in`, extract
   `char_type` and `traits_type` the same as `charT` and `traits`,
   respectively, then the expression `out << quoted(s, delim, escape)`
   behaves as specified for the
   `const basic_string<charT, traits, Allocator>&` overload of the
   `quoted` function.
+- The expression `in >> quoted(s, delim, escape)` has type
+ `basic_istream<charT, traits>&` and value `in`.
+- The expression `out << quoted(s, delim, escape)` has type
   `basic_ostream<charT, traits>&` and value `out`.
 ## String-based streams <a id="string.streams">[[string.streams]]</a>
 ### Header `<sstream>` synopsis <a id="sstream.syn">[[sstream.syn]]</a>
     using off_type       = typename traits::off_type;
     using traits_type    = traits;
     using allocator_type = Allocator;
     // [stringbuf.cons], constructors
+    basic_stringbuf() : basic_stringbuf(ios_base::in | ios_base::out) {}
+    explicit basic_stringbuf(ios_base::openmode which);
     explicit basic_stringbuf(
+      const basic_string<charT, traits, Allocator>& s,
       ios_base::openmode which = ios_base::in | ios_base::out);
+    explicit basic_stringbuf(const Allocator& a)
+      : basic_stringbuf(ios_base::in | ios_base::out, a) {}
+    basic_stringbuf(ios_base::openmode which, const Allocator& a);
     explicit basic_stringbuf(
+      basic_string<charT, traits, Allocator>&& s,
       ios_base::openmode which = ios_base::in | ios_base::out);
+ template<class SAlloc>
+      basic_stringbuf(
+        const basic_string<charT, traits, SAlloc>& s, const Allocator& a)
+        : basic_stringbuf(s, ios_base::in | ios_base::out, a) {}
+    template<class SAlloc>
+      basic_stringbuf(
+        const basic_string<charT, traits, SAlloc>& s,
+        ios_base::openmode which, const Allocator& a);
+    template<class SAlloc>
+      explicit basic_stringbuf(
+        const basic_string<charT, traits, SAlloc>& s,
+        ios_base::openmode which = ios_base::in | ios_base::out);
+    basic_stringbuf(const basic_stringbuf&) = delete;
     basic_stringbuf(basic_stringbuf&& rhs);
+    basic_stringbuf(basic_stringbuf&& rhs, const Allocator& a);
     // [stringbuf.assign], assign and swap
+    basic_stringbuf& operator=(const basic_stringbuf&) = delete;
     basic_stringbuf& operator=(basic_stringbuf&& rhs);
+    void swap(basic_stringbuf& rhs) noexcept(see below);
+    // [stringbuf.members], getters and setters
+    allocator_type get_allocator() const noexcept;
+    basic_string<charT, traits, Allocator> str() const &;
+    template<class SAlloc>
+      basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const;
+    basic_string<charT, traits, Allocator> str() &&;
+    basic_string_view<charT, traits> view() const noexcept;
     void str(const basic_string<charT, traits, Allocator>& s);
+    template<class SAlloc>
+      void str(const basic_string<charT, traits, SAlloc>& s);
+    void str(basic_string<charT, traits, Allocator>&& s);
   protected:
     // [stringbuf.virtuals], overridden virtual functions
     int_type underflow() override;
     int_type pbackfail(int_type c = traits::eof()) override;
                      ios_base::openmode which
                       = ios_base::in | ios_base::out) override;
   private:
     ios_base::openmode mode;                        // exposition only
+    basic_string<charT, traits, Allocator> buf;     // exposition only
+    void init_buf_ptrs();                           // exposition only
   };
   template<class charT, class traits, class Allocator>
     void swap(basic_stringbuf<charT, traits, Allocator>& x,
+              basic_stringbuf<charT, traits, Allocator>& y) noexcept(noexcept(x.swap(y)));
 }
 ```
 The class `basic_stringbuf` is derived from `basic_streambuf` to
 associate possibly the input sequence and possibly the output sequence
 with a sequence of arbitrary *characters*. The sequence can be
 initialized from, or made available as, an object of class
 `basic_string`.
+For the sake of exposition, the maintained data and internal pointer
+initialization is presented here as:
 - `ios_base::openmode mode`, has `in` set if the input sequence can be
   read, and `out` set if the output sequence can be written.
+- `basic_string<charT, traits, Allocator> buf` contains the underlying
+  character sequence.
+- `init_buf_ptrs()` sets the base class’ get area [[streambuf.get.area]]
+  and put area [[streambuf.put.area]] pointers after initializing,
+  moving from, or assigning to `buf` accordingly.
+#### Constructors <a id="stringbuf.cons">[[stringbuf.cons]]</a>
 ``` cpp
+explicit basic_stringbuf(ios_base::openmode which);
 ```
+*Effects:* Initializes the base class with `basic_streambuf()`
+[[streambuf.cons]], and `mode` with `which`. It is
+*implementation-defined* whether the sequence pointers (`eback()`,
+`gptr()`, `egptr()`, `pbase()`, `pptr()`, `epptr()`) are initialized to
+null pointers.
+*Ensures:* `str().empty()` is `true`.
 ``` cpp
 explicit basic_stringbuf(
   const basic_string<charT, traits, Allocator>& s,
   ios_base::openmode which = ios_base::in | ios_base::out);
 ```
+*Effects:* Initializes the base class with `basic_streambuf()`
+[[streambuf.cons]], `mode` with `which`, and `buf` with `s`, then calls
+`init_buf_ptrs()`.
+``` cpp
+basic_stringbuf(ios_base::openmode which, const Allocator &a);
+```
+*Effects:* Initializes the base class with `basic_streambuf()`
+[[streambuf.cons]], `mode` with `which`, and `buf` with `a`, then calls
+`init_buf_ptrs()`.
+*Ensures:* `str().empty()` is `true`.
+``` cpp
+explicit basic_stringbuf(
+  basic_string<charT, traits, Allocator>&& s,
+  ios_base::openmode which = ios_base::in | ios_base::out);
+```
+*Effects:* Initializes the base class with `basic_streambuf()`
+[[streambuf.cons]], `mode` with `which`, and `buf` with `std::move(s)`,
+then calls `init_buf_ptrs()`.
+``` cpp
+template<class SAlloc>
+  basic_stringbuf(
+    const basic_string<charT, traits, SAlloc>& s,
+    ios_base::openmode which, const Allocator &a);
+```
+*Effects:* Initializes the base class with `basic_streambuf()`
+[[streambuf.cons]], `mode` with `which`, and `buf` with `{s,a}`, then
+calls `init_buf_ptrs()`.
+``` cpp
+template<class SAlloc>
+  explicit basic_stringbuf(
+    const basic_string<charT, traits, SAlloc>& s,
+    ios_base::openmode which = ios_base::in | ios_base::out);
+```
+*Constraints:* `is_same_v<SAlloc,Allocator>` is `false`.
+*Effects:* Initializes the base class with `basic_streambuf()`
+[[streambuf.cons]], `mode` with `which`, and `buf` with `s`, then calls
+`init_buf_ptrs()`.
 ``` cpp
 basic_stringbuf(basic_stringbuf&& rhs);
+basic_stringbuf(basic_stringbuf&& rhs, const Allocator& a);
 ```
+*Effects:* Copy constructs the base class from `rhs` and initializes
+`mode` with `rhs.mode`. In the first form `buf` is initialized from
+`std::move(rhs).str()`. In the second form `buf` is initialized from
+`{std::move(rhs).str(), a}`. It is *implementation-defined* whether the
+sequence pointers in `*this` (`eback()`, `gptr()`, `egptr()`, `pbase()`,
+`pptr()`, `epptr()`) obtain the values which `rhs` had.
+*Ensures:* Let `rhs_p` refer to the state of `rhs` just prior to this
+construction and let `rhs_a` refer to the state of `rhs` just after this
+construction.
 - `str() == rhs_p.str()`
 - `gptr() - eback() == rhs_p.gptr() - rhs_p.eback()`
 - `egptr() - eback() == rhs_p.egptr() - rhs_p.eback()`
 - `pptr() - pbase() == rhs_p.pptr() - rhs_p.pbase()`
 - `if (gptr()) gptr() != rhs_a.gptr()`
 - `if (egptr()) egptr() != rhs_a.egptr()`
 - `if (pbase()) pbase() != rhs_a.pbase()`
 - `if (pptr()) pptr() != rhs_a.pptr()`
 - `if (epptr()) epptr() != rhs_a.epptr()`
+- `getloc() == rhs_p.getloc()`
+- `rhs` is empty but usable, as if `std::move(rhs).str()` was called.
+#### Assignment and swap <a id="stringbuf.assign">[[stringbuf.assign]]</a>
 ``` cpp
 basic_stringbuf& operator=(basic_stringbuf&& rhs);
 ```
 (see  [[stringbuf.cons]]).
 *Returns:* `*this`.
 ``` cpp
+void swap(basic_stringbuf& rhs) noexcept(see below);
 ```
+*Preconditions:*
+`allocator_traits<Allocator>::propagate_on_container_swap::value` is
+`true` or `get_allocator() == s.get_allocator()` is `true`.
 *Effects:* Exchanges the state of `*this` and `rhs`.
+*Remarks:* The expression inside `noexcept` is equivalent to:
+`allocator_traits<Allocator>::propagate_on_container_swap::value ||`
+`allocator_traits<Allocator>::is_always_equal::value`.
 ``` cpp
 template<class charT, class traits, class Allocator>
   void swap(basic_stringbuf<charT, traits, Allocator>& x,
+            basic_stringbuf<charT, traits, Allocator>& y) noexcept(noexcept(x.swap(y)));
 ```
+*Effects:* Equivalent to: `x.swap(y)`.
 #### Member functions <a id="stringbuf.members">[[stringbuf.members]]</a>
+The member functions getting the underlying character sequence all refer
+to a `high_mark` value, where `high_mark` represents the position one
+past the highest initialized character in the buffer. Characters can be
+initialized by writing to the stream, by constructing the
+`basic_stringbuf` passing a `basic_string` argument, or by calling one
+of the `str` member functions passing a `basic_string` as an argument.
+In the latter case, all characters initialized prior to the call are now
+considered uninitialized (except for those characters re-initialized by
+the new `basic_string`).
+``` cpp
+void init_buf_ptrs(); // exposition only
+```
+*Effects:* Initializes the input and output sequences from `buf`
+according to `mode`.
+*Ensures:*
+- If `ios_base::out` is set in `mode`, `pbase()` points to `buf.front()`
+  and `epptr() >= pbase() + buf.size()` is `true`;
+  - in addition, if `ios_base::ate` is set in `mode`,
+    `pptr() == pbase() + buf.size()` is `true`,
+  - otherwise `pptr() == pbase()` is `true`.
+- If `ios_base::in` is set in `mode`, `eback()` points to `buf.front()`,
+  and `(gptr() == eback() && egptr() == eback() + buf.size())` is
+  `true`.
+[*Note 1*: For efficiency reasons, stream buffer operations might
+violate invariants of `buf` while it is held encapsulated in the
+`basic_stringbuf`, e.g., by writing to characters in the range
+\[`buf.data() + buf.size()`, `buf.data() + buf.capacity()`). All
+operations retrieving a `basic_string` from `buf` ensure that the
+`basic_string` invariants hold on the returned value. — *end note*]
+``` cpp
+allocator_type get_allocator() const noexcept;
+```
+*Returns:* `buf.get_allocator()`.
+``` cpp
+basic_string<charT, traits, Allocator> str() const &;
+```
+*Effects:* Equivalent to:
+``` cpp
+return basic_string<charT, traits, Allocator>(view(), get_allocator());
+```
 ``` cpp
+template<class SAlloc>
+  basic_string<charT, traits, SAlloc> str(const SAlloc& sa) const;
+```
+*Constraints:* `SAlloc` is a type that qualifies as an
+allocator [[container.requirements.general]].
+*Effects:* Equivalent to:
+``` cpp
+return basic_string<charT, traits, SAlloc>(view(), sa);
+```
+``` cpp
+basic_string<charT, traits, Allocator> str() &&;
+```
+*Returns:* A `basic_string<charT, traits, Allocator>` object move
+constructed from the `basic_stringbuf`’s underlying character sequence
+in `buf`. This can be achieved by first adjusting `buf` to have the same
+content as `view()`.
+*Ensures:* The underlying character sequence `buf` is empty and
+`pbase()`, `pptr()`, `epptr()`, `eback()`, `gptr()`, and `egptr()` are
+initialized as if by calling `init_buf_ptrs()` with an empty `buf`.
+``` cpp
+basic_string_view<charT, traits> view() const noexcept;
+```
+Let `sv` be `basic_string_view<charT, traits>`.
+*Returns:* A `sv` object referring to the `basic_stringbuf`’s underlying
+character sequence in `buf`:
+- If `ios_base::out` is set in `mode`, then
+  `sv(pbase(), high_mark-pbase())` is returned.
+- Otherwise, if `ios_base::in` is set in `mode`, then
+  `sv(eback(), egptr()-eback())` is returned.
+- Otherwise, `sv()` is returned.
+[*Note 2*: Using the returned `sv` object after destruction or
+invalidation of the character sequence underlying `*this` is undefined
+behavior, unless `sv.empty()` is `true`. — *end note*]
 ``` cpp
 void str(const basic_string<charT, traits, Allocator>& s);
 ```
+*Effects:* Equivalent to:
+``` cpp
+buf = s;
+init_buf_ptrs();
+```
+``` cpp
+template<class SAlloc>
+  void str(const basic_string<charT, traits, SAlloc>& s);
+```
+*Constraints:* `is_same_v<SAlloc,Allocator>` is `false`.
+*Effects:* Equivalent to:
+``` cpp
+buf = s;
+init_buf_ptrs();
+```
+``` cpp
+void str(basic_string<charT, traits, Allocator>&& s);
+```
+*Effects:* Equivalent to:
+``` cpp
+buf = std::move(s);
+init_buf_ptrs();
+```
 #### Overridden virtual functions <a id="stringbuf.virtuals">[[stringbuf.virtuals]]</a>
 ``` cpp
 int_type underflow() override;
   `ios_base::out` is nonzero, assigns `c` to `*``gptr()`. Returns: `c`.
 - If `traits::eq_int_type(c, traits::eof())` returns `true` and if the
   input sequence has a putback position available, assigns `gptr() - 1`
   to `gptr()`. Returns: `traits::not_eof(c)`.
+*Returns:* As specified above, or `traits::eof()` to indicate failure.
 *Remarks:* If the function can succeed in more than one of these ways,
 it is unspecified which way is chosen.
 ``` cpp
   `traits::eof()`.
 *Remarks:* The function can alter the number of write positions
 available as a result of any call.
+*Returns:* As specified above, or `traits::eof()` to indicate failure.
+The function can make a write position available only if `ios_base::out`
+is set in `mode`. To make a write position available, the function
+reallocates (or initially allocates) an array object with a sufficient
+number of elements to hold the current array object (if any), plus at
+least one additional write position. If `ios_base::in` is set in `mode`,
+the function alters the read end pointer `egptr()` to point just past
+the new write position.
 ``` cpp
 pos_type seekoff(off_type off, ios_base::seekdir way,
                  ios_base::openmode which
                    = ios_base::in | ios_base::out) override;
 ```
 *Effects:* Alters the stream position within one of the controlled
+sequences, if possible, as indicated in [[stringbuf.seekoff.pos]].
+**Table: `seekoff` positioning** <a id="stringbuf.seekoff.pos">[stringbuf.seekoff.pos]</a>
 | Conditions                                                                                                                     | Result                                            |
+| ------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------- |
+| `ios_base::in` is set in `which`                                                                                               | positions the input sequence                      |
+| `ios_base::out` is set in `which`                                                                                              | positions the output sequence                     |
+| both `ios_base::in` and `ios_base::out` are set in `which` and either<br> `way == ios_base::beg` or<br> `way == ios_base::end` | positions both the input and the output sequences |
 | Otherwise                                                                                                                      | the positioning operation fails.                  |
+For a sequence to be positioned, the function determines `newoff` as
+indicated in [[stringbuf.seekoff.newoff]]. If the sequence’s next
+pointer (either `gptr()` or `pptr()`) is a null pointer and `newoff` is
+nonzero, the positioning operation fails.
+**Table: `newoff` values** <a id="stringbuf.seekoff.newoff">[stringbuf.seekoff.newoff]</a>
 | Condition              | `newoff` Value                                                          |
 | ---------------------- | ----------------------------------------------------------------------- |
 | `way == ios_base::beg` | 0                                                                       |
 | `way == ios_base::cur` | the next pointer minus the beginning pointer (`xnext - xbeg`).          |
 | `way == ios_base::end` | the high mark pointer minus the beginning pointer (`high_mark - xbeg`). |
 If `(newoff + off) < 0`, or if `newoff + off` refers to an uninitialized
+character [[stringbuf.members]], the positioning operation fails.
 Otherwise, the function assigns `xbeg + newoff + off` to the next
 pointer `xnext`.
 *Returns:* `pos_type(newoff)`, constructed from the resultant offset
 `newoff` (of type `off_type`), that stores the resultant stream
     using off_type       = typename traits::off_type;
     using traits_type    = traits;
     using allocator_type = Allocator;
     // [istringstream.cons], constructors
+    basic_istringstream() : basic_istringstream(ios_base::in) {}
+    explicit basic_istringstream(ios_base::openmode which);
     explicit basic_istringstream(
+      const basic_string<charT, traits, Allocator>& s,
       ios_base::openmode which = ios_base::in);
+    basic_istringstream(ios_base::openmode which, const Allocator& a);
     explicit basic_istringstream(
+      basic_string<charT, traits, Allocator>&& s,
       ios_base::openmode which = ios_base::in);
+ template<class SAlloc>
+      basic_istringstream(
+        const basic_string<charT, traits, SAlloc>& s, const Allocator& a)
+        : basic_istringstream(s, ios_base::in, a) {}
+    template<class SAlloc>
+      basic_istringstream(
+        const basic_string<charT, traits, SAlloc>& s,
+        ios_base::openmode which, const Allocator& a);
+    template<class SAlloc>
+      explicit basic_istringstream(
+        const basic_string<charT, traits, SAlloc>& s,
+        ios_base::openmode which = ios_base::in);
+    basic_istringstream(const basic_istringstream&) = delete;
     basic_istringstream(basic_istringstream&& rhs);
     // [istringstream.assign], assign and swap
+    basic_istringstream& operator=(const basic_istringstream&) = delete;
     basic_istringstream& operator=(basic_istringstream&& rhs);
     void swap(basic_istringstream& rhs);
     // [istringstream.members], members
     basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
+    basic_string<charT, traits, Allocator> str() const &;
+    template<class SAlloc>
+      basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const;
+    basic_string<charT, traits, Allocator> str() &&;
+    basic_string_view<charT, traits> view() const noexcept;
     void str(const basic_string<charT, traits, Allocator>& s);
+    template<class SAlloc>
+      void str(const basic_string<charT, traits, SAlloc>& s);
+    void str(basic_string<charT, traits, Allocator>&& s);
   private:
     basic_stringbuf<charT, traits, Allocator> sb;   // exposition only
   };
   template<class charT, class traits, class Allocator>
 associated storage. For the sake of exposition, the maintained data is
 presented here as:
 - `sb`, the `stringbuf` object.
+#### Constructors <a id="istringstream.cons">[[istringstream.cons]]</a>
 ``` cpp
+explicit basic_istringstream(ios_base::openmode which);
 ```
+*Effects:* Initializes the base class with
+`basic_istream<charT, traits>(addressof(sb))` [[istream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(which | ios_base::in)`
+[[stringbuf.cons]].
 ``` cpp
 explicit basic_istringstream(
+  const basic_string<charT, traits, Allocator>& s,
   ios_base::openmode which = ios_base::in);
 ```
+*Effects:* Initializes the base class with
+`basic_istream<charT, traits>(addressof(sb))` [[istream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(s, which | ios_base::in)`([[stringbuf.cons]]).
+``` cpp
+basic_istringstream(ios_base::openmode which, const Allocator& a);
+```
+*Effects:* Initializes the base class with
+`basic_istream<charT, traits>(addressof(sb))` [[istream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(which | ios_base::in, a)`
+[[stringbuf.cons]].
+``` cpp
+explicit basic_istringstream(
+  basic_string<charT, traits, Allocator>&& s,
+  ios_base::openmode which = ios_base::in);
+```
+*Effects:* Initializes the base class with
+`basic_istream<charT, traits>(addressof(sb))` [[istream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(std::move(s), which | ios_base::in)`
+[[stringbuf.cons]].
+``` cpp
+template<class SAlloc>
+  basic_istringstream(
+    const basic_string<charT, traits, SAlloc>& s,
+    ios_base::openmode which, const Allocator& a);
+```
+*Effects:* Initializes the base class with
+`basic_istream<charT, traits>(addressof(sb))` [[istream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(s, which | ios_base::in, a)`([[stringbuf.cons]]).
+``` cpp
+template<class SAlloc>
+  explicit basic_istringstream(
+    const basic_string<charT, traits, SAlloc>& s,
+    ios_base::openmode which = ios_base::in);
+```
+*Effects:* Initializes the base class with
+`basic_istream<charT, traits>(addressof(sb))` [[istream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(s, which | ios_base::in)`
+[[stringbuf.cons]].
 ``` cpp
 basic_istringstream(basic_istringstream&& rhs);
 ```
 *Effects:* Move constructs from the rvalue `rhs`. This is accomplished
 by move constructing the base class, and the contained
+`basic_stringbuf`. Then calls
+`basic_istream<charT, traits>::set_rdbuf(addressof(sb))` to install the
+contained `basic_stringbuf`.
+#### Assignment and swap <a id="istringstream.assign">[[istringstream.assign]]</a>
 ``` cpp
 void swap(basic_istringstream& rhs);
 ```
+*Effects:* Equivalent to:
+``` cpp
+basic_istream<charT, traits>::swap(rhs);
+sb.swap(rhs.sb);
+```
 ``` cpp
 template<class charT, class traits, class Allocator>
   void swap(basic_istringstream<charT, traits, Allocator>& x,
             basic_istringstream<charT, traits, Allocator>& y);
 ```
+*Effects:* Equivalent to: `x.swap(y)`.
 #### Member functions <a id="istringstream.members">[[istringstream.members]]</a>
 ``` cpp
 basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
 ```
 *Returns:*
+`const_cast<basic_stringbuf<charT, traits, Allocator>*>(addressof(sb))`.
 ``` cpp
+basic_string<charT, traits, Allocator> str() const &;
 ```
+*Effects:* Equivalent to: `return rdbuf()->str();`
+``` cpp
+template<class SAlloc>
+  basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const;
+```
+*Effects:* Equivalent to: `return rdbuf()->str(sa);`
+``` cpp
+basic_string<charT,traits,Allocator> str() &&;
+```
+*Effects:* Equivalent to: `return std::move(*rdbuf()).str();`
+``` cpp
+basic_string_view<charT, traits> view() const noexcept;
+```
+*Effects:* Equivalent to: `return rdbuf()->view();`
 ``` cpp
 void str(const basic_string<charT, traits, Allocator>& s);
 ```
+*Effects:* Equivalent to: `rdbuf()->str(s);`
+``` cpp
+template<class SAlloc>
+  void str(const basic_string<charT, traits, SAlloc>& s);
+```
+*Effects:* Equivalent to: `rdbuf()->str(s);`
+``` cpp
+void str(basic_string<charT, traits, Allocator>&& s);
+```
+*Effects:* Equivalent to: `rdbuf()->str(std::move(s));`
 ### Class template `basic_ostringstream` <a id="ostringstream">[[ostringstream]]</a>
 ``` cpp
 namespace std {
     using off_type       = typename traits::off_type;
     using traits_type    = traits;
     using allocator_type = Allocator;
     // [ostringstream.cons], constructors
+    basic_ostringstream() : basic_ostringstream(ios_base::out) {}
+    explicit basic_ostringstream(ios_base::openmode which);
     explicit basic_ostringstream(
+      const basic_string<charT, traits, Allocator>& s,
       ios_base::openmode which = ios_base::out);
+    basic_ostringstream(ios_base::openmode which, const Allocator& a);
     explicit basic_ostringstream(
+      basic_string<charT, traits, Allocator>&& s,
       ios_base::openmode which = ios_base::out);
+ template<class SAlloc>
+      basic_ostringstream(
+        const basic_string<charT, traits, SAlloc>& s, const Allocator& a)
+        : basic_ostringstream(s, ios_base::out, a) {}
+    template<class SAlloc>
+      basic_ostringstream(
+        const basic_string<charT, traits, SAlloc>& s,
+        ios_base::openmode which, const Allocator& a);
+    template<class SAlloc>
+      explicit basic_ostringstream(
+        const basic_string<charT, traits, SAlloc>& s,
+        ios_base::openmode which = ios_base::out);
+    basic_ostringstream(const basic_ostringstream&) = delete;
     basic_ostringstream(basic_ostringstream&& rhs);
     // [ostringstream.assign], assign and swap
+    basic_ostringstream& operator=(const basic_ostringstream&) = delete;
     basic_ostringstream& operator=(basic_ostringstream&& rhs);
     void swap(basic_ostringstream& rhs);
     // [ostringstream.members], members
     basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
+    basic_string<charT, traits, Allocator> str() const &;
+    template<class SAlloc>
+      basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const;
+    basic_string<charT, traits, Allocator> str() &&;
+    basic_string_view<charT, traits> view() const noexcept;
     void str(const basic_string<charT, traits, Allocator>& s);
+    template<class SAlloc>
+      void str(const basic_string<charT, traits, SAlloc>& s);
+    void str(basic_string<charT, traits, Allocator>&& s);
    private:
     basic_stringbuf<charT, traits, Allocator> sb;   // exposition only
   };
   template<class charT, class traits, class Allocator>
 uses a `basic_stringbuf` object to control the associated storage. For
 the sake of exposition, the maintained data is presented here as:
 - `sb`, the `stringbuf` object.
+#### Constructors <a id="ostringstream.cons">[[ostringstream.cons]]</a>
+``` cpp
+explicit basic_ostringstream(ios_base::openmode which);
+```
+*Effects:* Initializes the base class with
+`basic_ostream<charT, traits>(addressof(sb))` [[ostream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(which | ios_base::out)`
+[[stringbuf.cons]].
 ``` cpp
 explicit basic_ostringstream(
+  const basic_string<charT, traits, Allocator>& s,
   ios_base::openmode which = ios_base::out);
 ```
+*Effects:* Initializes the base class with
+`basic_ostream<charT, traits>(addressof(sb))` [[ostream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(s, which | ios_base::out)`([[stringbuf.cons]]).
+``` cpp
+basic_ostringstream(ios_base::openmode which, const Allocator& a);
+```
+*Effects:* Initializes the base class with
+`basic_ostream<charT, traits>(addressof(sb))` [[ostream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(which | ios_base::out, a)`([[stringbuf.cons]]).
 ``` cpp
 explicit basic_ostringstream(
+  basic_string<charT, traits, Allocator>&& s,
   ios_base::openmode which = ios_base::out);
 ```
+*Effects:* Initializes the base class with
+`basic_ostream<charT, traits>(addressof(sb))` [[ostream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(std::move(s), which | ios_base::out)`
+[[stringbuf.cons]].
+``` cpp
+template<class SAlloc>
+  basic_ostringstream(
+    const basic_string<charT, traits, SAlloc>& s,
+    ios_base::openmode which, const Allocator& a);
+```
+*Effects:* Initializes the base class with
+`basic_ostream<charT, traits>(addressof(sb))` [[ostream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(s, which | ios_base::out, a)`([[stringbuf.cons]]).
+``` cpp
+template<class SAlloc>
+  explicit basic_ostringstream(
+    const basic_string<charT, traits, SAlloc>& s,
+    ios_base::openmode which = ios_base::out);
+```
+*Constraints:* `is_same_v<SAlloc,Allocator>` is `false`.
+*Effects:* Initializes the base class with
+`basic_ostream<charT, traits>(addressof(sb))` [[ostream]] and `sb` with
+`basic_stringbuf<charT, traits, Allocator>(s, which | ios_base::out)`([[stringbuf.cons]]).
 ``` cpp
 basic_ostringstream(basic_ostringstream&& rhs);
 ```
 *Effects:* Move constructs from the rvalue `rhs`. This is accomplished
 by move constructing the base class, and the contained
+`basic_stringbuf`. Then calls
+`basic_ostream<charT, traits>::set_rdbuf(addressof(sb))` to install the
+contained `basic_stringbuf`.
+#### Assignment and swap <a id="ostringstream.assign">[[ostringstream.assign]]</a>
 ``` cpp
 void swap(basic_ostringstream& rhs);
 ```
+*Effects:* Equivalent to:
+``` cpp
+basic_ostream<charT, traits>::swap(rhs);
+sb.swap(rhs.sb);
+```
 ``` cpp
 template<class charT, class traits, class Allocator>
   void swap(basic_ostringstream<charT, traits, Allocator>& x,
             basic_ostringstream<charT, traits, Allocator>& y);
 ```
+*Effects:* Equivalent to: `x.swap(y)`.
 #### Member functions <a id="ostringstream.members">[[ostringstream.members]]</a>
 ``` cpp
 basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
 ```
 *Returns:*
+`const_cast<basic_stringbuf<charT, traits, Allocator>*>(addressof(sb))`.
 ``` cpp
+basic_string<charT, traits, Allocator> str() const &;
 ```
+*Effects:* Equivalent to: `return rdbuf()->str();`
+``` cpp
+template<class SAlloc>
+  basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const;
+```
+*Effects:* Equivalent to: `return rdbuf()->str(sa);`
+``` cpp
+basic_string<charT,traits,Allocator> str() &&;
+```
+*Effects:* Equivalent to: `return std::move(*rdbuf()).str();`
+``` cpp
+basic_string_view<charT, traits> view() const noexcept;
+```
+*Effects:* Equivalent to: `return rdbuf()->view();`
 ``` cpp
 void str(const basic_string<charT, traits, Allocator>& s);
 ```
+*Effects:* Equivalent to: `rdbuf()->str(s);`
+``` cpp
+template<class SAlloc>
+  void str(const basic_string<charT, traits, SAlloc>& s);
+```
+*Effects:* Equivalent to: `rdbuf()->str(s);`
+``` cpp
+void str(basic_string<charT, traits, Allocator>&& s);
+```
+*Effects:* Equivalent to: `rdbuf()->str(std::move(s));`
 ### Class template `basic_stringstream` <a id="stringstream">[[stringstream]]</a>
 ``` cpp
 namespace std {
     using off_type       = typename traits::off_type;
     using traits_type    = traits;
     using allocator_type = Allocator;
     // [stringstream.cons], constructors
+    basic_stringstream() : basic_stringstream(ios_base::out | ios_base::in) {}
+    explicit basic_stringstream(ios_base::openmode which);
     explicit basic_stringstream(
+      const basic_string<charT, traits, Allocator>& s,
       ios_base::openmode which = ios_base::out | ios_base::in);
+    basic_stringstream(ios_base::openmode which, const Allocator& a);
     explicit basic_stringstream(
+      basic_string<charT, traits, Allocator>&& s,
       ios_base::openmode which = ios_base::out | ios_base::in);
+ template<class SAlloc>
+      basic_stringstream(
+        const basic_string<charT, traits, SAlloc>& s, const Allocator& a)
+        : basic_stringstream(s, ios_base::out | ios_base::in, a) {}
+    template<class SAlloc>
+      basic_stringstream(
+        const basic_string<charT, traits, SAlloc>& s,
+        ios_base::openmode which, const Allocator& a);
+    template<class SAlloc>
+      explicit basic_stringstream(
+        const basic_string<charT, traits, SAlloc>& s,
+        ios_base::openmode which = ios_base::out | ios_base::in);
+    basic_stringstream(const basic_stringstream&) = delete;
     basic_stringstream(basic_stringstream&& rhs);
     // [stringstream.assign], assign and swap
+    basic_stringstream& operator=(const basic_stringstream&) = delete;
     basic_stringstream& operator=(basic_stringstream&& rhs);
     void swap(basic_stringstream& rhs);
     // [stringstream.members], members
     basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
+    basic_string<charT, traits, Allocator> str() const &;
+    template<class SAlloc>
+      basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const;
+    basic_string<charT, traits, Allocator> str() &&;
+    basic_string_view<charT, traits> view() const noexcept;
+    void str(const basic_string<charT, traits, Allocator>& s);
+    template<class SAlloc>
+      void str(const basic_string<charT, traits, SAlloc>& s);
+    void str(basic_string<charT, traits, Allocator>&& s);
   private:
     basic_stringbuf<charT, traits> sb;  // exposition only
   };
 associated sequence. For the sake of exposition, the maintained data is
 presented here as
 - `sb`, the `stringbuf` object.
+#### Constructors <a id="stringstream.cons">[[stringstream.cons]]</a>
+``` cpp
+explicit basic_stringstream(ios_base::openmode which);
+```
+*Effects:* Initializes the base class with
+`basic_iostream<charT, traits>(addressof(sb))` [[iostream.cons]] and
+`sb` with `basic_stringbuf<charT, traits, Allocator>(which)`.
 ``` cpp
 explicit basic_stringstream(
+  const basic_string<charT, traits, Allocator>& s,
   ios_base::openmode which = ios_base::out | ios_base::in);
 ```
+*Effects:* Initializes the base class with
+`basic_iostream<charT, traits>(addressof(sb))` [[iostream.cons]] and
+`sb` with `basic_stringbuf<charT, traits, Allocator>(s, which)`.
+``` cpp
+basic_stringstream(ios_base::openmode which, const Allocator& a);
+```
+*Effects:* Initializes the base class with
+`basic_iostream<charT, traits>(addressof(sb))` [[iostream.cons]] and
+`sb` with `basic_stringbuf<charT, traits, Allocator>(which, a)`
+[[stringbuf.cons]].
 ``` cpp
 explicit basic_stringstream(
+  basic_string<charT, traits, Allocator>&& s,
   ios_base::openmode which = ios_base::out | ios_base::in);
 ```
+*Effects:* Initializes the base class with
+`basic_iostream<charT, traits>(addressof(sb))` [[iostream.cons]] and
+`sb` with
+`basic_stringbuf<charT, traits, Allocator>(std::move(s), which)`
+[[stringbuf.cons]].
+``` cpp
+template<class SAlloc>
+  basic_stringstream(
+    const basic_string<charT, traits, SAlloc>& s,
+    ios_base::openmode which, const Allocator& a);
+```
+*Effects:* Initializes the base class with
+`basic_iostream<charT, traits>(addressof(sb))` [[iostream.cons]] and
+`sb` with `basic_stringbuf<charT, traits, Allocator>(s, which, a)`
+[[stringbuf.cons]].
+``` cpp
+template<class SAlloc>
+  explicit basic_stringstream(
+    const basic_string<charT, traits, SAlloc>& s,
+    ios_base::openmode which = ios_base::out | ios_base::in);
+```
+*Constraints:* `is_same_v<SAlloc,Allocator>` is `false`.
+*Effects:* Initializes the base class with
+`basic_iostream<charT, traits>(addressof(sb))` [[iostream.cons]] and
+`sb` with `basic_stringbuf<charT, traits, Allocator>(s, which)`
+[[stringbuf.cons]].
 ``` cpp
 basic_stringstream(basic_stringstream&& rhs);
 ```
 *Effects:* Move constructs from the rvalue `rhs`. This is accomplished
 by move constructing the base class, and the contained
+`basic_stringbuf`. Then calls
+`basic_istream<charT, traits>::set_rdbuf(addressof(sb))` to install the
+contained `basic_stringbuf`.
+#### Assignment and swap <a id="stringstream.assign">[[stringstream.assign]]</a>
 ``` cpp
 void swap(basic_stringstream& rhs);
 ```
+*Effects:* Equivalent to:
+``` cpp
+basic_iostream<charT,traits>::swap(rhs);
+sb.swap(rhs.sb);
+```
 ``` cpp
 template<class charT, class traits, class Allocator>
   void swap(basic_stringstream<charT, traits, Allocator>& x,
             basic_stringstream<charT, traits, Allocator>& y);
 ```
+*Effects:* Equivalent to: `x.swap(y)`.
 #### Member functions <a id="stringstream.members">[[stringstream.members]]</a>
 ``` cpp
 basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
 ```
+*Returns:*
+`const_cast<basic_stringbuf<charT, traits, Allocator>*>(addressof(sb))`.
 ``` cpp
+basic_string<charT, traits, Allocator> str() const &;
 ```
+*Effects:* Equivalent to: `return rdbuf()->str();`
 ``` cpp
+template<class SAlloc>
+  basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const;
 ```
+*Effects:* Equivalent to: `return rdbuf()->str(sa);`
+``` cpp
+basic_string<charT,traits,Allocator> str() &&;
+```
+*Effects:* Equivalent to: `return std::move(*rdbuf()).str();`
+``` cpp
+basic_string_view<charT, traits> view() const noexcept;
+```
+*Effects:* Equivalent to: `return rdbuf()->view();`
+``` cpp
+void str(const basic_string<charT, traits, Allocator>& s);
+```
+*Effects:* Equivalent to: `rdbuf()->str(s);`
+``` cpp
+template<class SAlloc>
+  void str(const basic_string<charT, traits, SAlloc>& s);
+```
+*Effects:* Equivalent to: `rdbuf()->str(s);`
+``` cpp
+void str(basic_string<charT, traits, Allocator>&& s);
+```
+*Effects:* Equivalent to: `rdbuf()->str(std::move(s));`
 ## File-based streams <a id="file.streams">[[file.streams]]</a>
 ### Header `<fstream>` synopsis <a id="fstream.syn">[[fstream.syn]]</a>
 or sink of bytes. In an environment that uses a large character set, the
 file typically holds multibyte character sequences and the
 `basic_filebuf` object converts those multibyte sequences into wide
 character sequences. — *end note*]
+In subclause  [[file.streams]], member functions taking arguments of
 `const filesystem::path::value_type*` are only be provided on systems
+where `filesystem::path::value_type` [[fs.class.path]] is not `char`.
 [*Note 2*: These functions enable class `path` support for systems with
 a wide native path character type, such as `wchar_t`. — *end note*]
 ### Class template `basic_filebuf` <a id="filebuf">[[filebuf]]</a>
     using off_type    = typename traits::off_type;
     using traits_type = traits;
     // [filebuf.cons], constructors/destructor
     basic_filebuf();
+    basic_filebuf(const basic_filebuf&) = delete;
     basic_filebuf(basic_filebuf&& rhs);
     virtual ~basic_filebuf();
     // [filebuf.assign], assign and swap
+    basic_filebuf& operator=(const basic_filebuf&) = delete;
     basic_filebuf& operator=(basic_filebuf&& rhs);
     void swap(basic_filebuf& rhs);
     // [filebuf.members], members
     bool is_open() const;
 provided `traits::pos_type` is `fpos<traits::{}state_type>`. Otherwise
 the behavior is undefined.
 In order to support file I/O and multibyte/wide character conversion,
 conversions are performed using members of a facet, referred to as
+`a_codecvt` in following subclauses, obtained as if by
 ``` cpp
 const codecvt<charT, char, typename traits::state_type>& a_codecvt =
   use_facet<codecvt<charT, char, typename traits::state_type>>(getloc());
 ```
+#### Constructors <a id="filebuf.cons">[[filebuf.cons]]</a>
 ``` cpp
 basic_filebuf();
 ```
+*Effects:* Initializes the base class with
+`basic_streambuf<charT, traits>()` [[streambuf.cons]].
+*Ensures:* `is_open() == false`.
 ``` cpp
 basic_filebuf(basic_filebuf&& rhs);
 ```
+*Effects:* It is *implementation-defined* whether the sequence pointers
+in `*this` (`eback()`, `gptr()`, `egptr()`, `pbase()`, `pptr()`,
+`epptr()`) obtain the values which `rhs` had. Whether they do or not,
+`*this` and `rhs` reference separate buffers (if any at all) after the
+construction. Additionally `*this` references the file which `rhs` did
+before the construction, and `rhs` references no file after the
+construction. The openmode, locale and any other state of `rhs` is also
+copied.
+*Ensures:* Let `rhs_p` refer to the state of `rhs` just prior to this
+construction and let `rhs_a` refer to the state of `rhs` just after this
+construction.
 - `is_open() == rhs_p.is_open()`
 - `rhs_a.is_open() == false`
 - `gptr() - eback() == rhs_p.gptr() - rhs_p.eback()`
 - `egptr() - eback() == rhs_p.egptr() - rhs_p.eback()`
 ``` cpp
 virtual ~basic_filebuf();
 ```
+*Effects:* Calls `close()`. If an exception occurs during the
+destruction of the object, including the call to `close()`, the
+exception is caught but not rethrown
+(see  [[res.on.exception.handling]]).
+#### Assignment and swap <a id="filebuf.assign">[[filebuf.assign]]</a>
 ``` cpp
 basic_filebuf& operator=(basic_filebuf&& rhs);
 ```
 template<class charT, class traits>
   void swap(basic_filebuf<charT, traits>& x,
             basic_filebuf<charT, traits>& y);
 ```
+*Effects:* Equivalent to: `x.swap(y)`.
 #### Member functions <a id="filebuf.members">[[filebuf.members]]</a>
 ``` cpp
 bool is_open() const;
 basic_filebuf* open(const char* s, ios_base::openmode mode);
 basic_filebuf* open(const filesystem::path::value_type* s,
                     ios_base::openmode mode);  // wide systems only; see [fstream.syn]
 ```
+*Preconditions:* `s` points to a NTCTS [[defns.ntcts]].
 *Effects:* If `is_open() != false`, returns a null pointer. Otherwise,
+initializes the `filebuf` as required. It then opens the file to which
+`s` resolves, if possible, as if by a call to `fopen` with the second
+argument determined from `mode & ~ios_base::ate` as indicated in
+[[filebuf.open.modes]]. If `mode` is not some combination of flags shown
+in the table then the open fails.
+**Table: File open modes** <a id="filebuf.open.modes">[filebuf.open.modes]</a>
 | `binary` | `in` | `out` | `trunc` | `app` |     | `stdio` equivalent |
 | -------- | ---- | ----- | ------- | ----- | --- | ------------------ |
 |          |      | +     |         |       | `"w"` |
 |          |      | +     |         | +     | `"a"` |
 | +        | +    | +     | +       |       | `"w+b"` |
 | +        | +    | +     |         | +     | `"a+b"` |
 | +        | +    |       |         | +     | `"a+b"` |
+If the open operation succeeds and `ios_base::ate` is set in `mode`,
 positions the file to the end (as if by calling
+`fseek(file, 0, SEEK_END)`, where `file` is the pointer returned by
+calling `fopen`). [^40]
 If the repositioning operation fails, calls `close()` and returns a null
 pointer to indicate failure.
 *Returns:* `this` if successful, a null pointer otherwise.
 these calls throws an exception, the exception is caught and rethrown
 after closing the file.
 *Returns:* `this` on success, a null pointer otherwise.
+*Ensures:* `is_open() == false`.
 #### Overridden virtual functions <a id="filebuf.virtuals">[[filebuf.virtuals]]</a>
 ``` cpp
 streamsize showmanyc() override;
 ```
+*Effects:* Behaves the same as `basic_streambuf::showmanyc()`
+[[streambuf.virtuals]].
 *Remarks:* An implementation might well provide an overriding definition
 for this function signature if it can determine that more characters can
 be read from the input sequence.
   either the input sequence has a putback position available or the
   function makes a putback position available, decrements the next
   pointer for the input sequence, `gptr()`. Returns:
   `traits::not_eof(c)`.
+*Returns:* As specified above, or `traits::eof()` to indicate failure.
 *Remarks:* If `is_open() == false`, the function always fails.
 The function does not put back a character directly to the input
 sequence.
 operation was overflow or the put buffer is non-empty. “Write any
 unshift sequence” means, if `width` if less than zero then call
 `a_codecvt.unshift(state, xbuf, xbuf+XSIZE, xbuf_end)` and output the
 resulting unshift sequence. The function determines one of three values
 for the argument `whence`, of type `int`, as indicated in
+[[filebuf.seekoff]].
+**Table: `seekoff` effects** <a id="filebuf.seekoff">[filebuf.seekoff]</a>
 | `way` Value      | `stdio` Equivalent |
 | ---------------- | ------------------ |
 | `basic_ios::beg` | `SEEK_SET`         |
 | `basic_ios::cur` | `SEEK_CUR`         |
 ``` cpp
 void imbue(const locale& loc) override;
 ```
+*Preconditions:* If the file is not positioned at its beginning and the
 encoding of the current locale as determined by `a_codecvt.encoding()`
+is state-dependent [[locale.codecvt.virtuals]] then that facet is the
 same as the corresponding facet of `loc`.
 *Effects:* Causes characters inserted or extracted after this call to be
 converted according to `loc` until another call of `imbue`.
                             ios_base::openmode mode = ios_base::in);// wide systems only; see [fstream.syn]
     explicit basic_ifstream(const string& s,
                             ios_base::openmode mode = ios_base::in);
     explicit basic_ifstream(const filesystem::path& s,
                             ios_base::openmode mode = ios_base::in);
+    basic_ifstream(const basic_ifstream&) = delete;
     basic_ifstream(basic_ifstream&& rhs);
     // [ifstream.assign], assign and swap
+    basic_ifstream& operator=(const basic_ifstream&) = delete;
     basic_ifstream& operator=(basic_ifstream&& rhs);
     void swap(basic_ifstream& rhs);
     // [ifstream.members], members
     basic_filebuf<charT, traits>* rdbuf() const;
 associated sequence. For the sake of exposition, the maintained data is
 presented here as:
 - `sb`, the `filebuf` object.
+#### Constructors <a id="ifstream.cons">[[ifstream.cons]]</a>
 ``` cpp
 basic_ifstream();
 ```
+*Effects:* Initializes the base class with
+`basic_istream<charT, traits>(addressof(sb))` [[istream.cons]] and `sb`
+with `basic_filebuf<charT, traits>()` [[filebuf.cons]].
 ``` cpp
 explicit basic_ifstream(const char* s,
                         ios_base::openmode mode = ios_base::in);
 explicit basic_ifstream(const filesystem::path::value_type* s,
                         ios_base::openmode mode = ios_base::in);  // wide systems only; see [fstream.syn]
 ```
+*Effects:* Initializes the base class with
+`basic_istream<charT, traits>(addressof(sb))` [[istream.cons]] and `sb`
+with `basic_filebuf<charT, traits>()` [[filebuf.cons]], then calls
+`rdbuf()->open(s, mode | ios_base::in)`. If that function returns a null
+pointer, calls `setstate(failbit)`.
 ``` cpp
 explicit basic_ifstream(const string& s,
                         ios_base::openmode mode = ios_base::in);
 explicit basic_ifstream(const filesystem::path& s,
                         ios_base::openmode mode = ios_base::in);
 ```
+*Effects:* Equivalent to: `basic_ifstream(s.c_str(), mode)`.
 ``` cpp
 basic_ifstream(basic_ifstream&& rhs);
 ```
+*Effects:* Move constructs the base class, and the contained
+`basic_filebuf`. Then calls
+`basic_istream<charT, traits>::set_rdbuf(addressof(sb))` to install the
+contained `basic_filebuf`.
+#### Assignment and swap <a id="ifstream.assign">[[ifstream.assign]]</a>
 ``` cpp
 void swap(basic_ifstream& rhs);
 ```
 template<class charT, class traits>
   void swap(basic_ifstream<charT, traits>& x,
             basic_ifstream<charT, traits>& y);
 ```
+*Effects:* Equivalent to: `x.swap(y)`.
 #### Member functions <a id="ifstream.members">[[ifstream.members]]</a>
 ``` cpp
 basic_filebuf<charT, traits>* rdbuf() const;
 ```
+*Returns:* `const_cast<basic_filebuf<charT, traits>*>(addressof(sb))`.
 ``` cpp
 bool is_open() const;
 ```
           ios_base::openmode mode = ios_base::in);  // wide systems only; see [fstream.syn]
 ```
 *Effects:* Calls `rdbuf()->open(s, mode | ios_base::in)`. If that
 function does not return a null pointer calls `clear()`, otherwise calls
+`setstate(failbit)` (which may throw
+`ios_base::failure`) [[iostate.flags]].
 ``` cpp
 void open(const string& s, ios_base::openmode mode = ios_base::in);
 void open(const filesystem::path& s, ios_base::openmode mode = ios_base::in);
 ```
 void close();
 ```
 *Effects:* Calls `rdbuf()->close()` and, if that function returns a null
 pointer, calls `setstate(failbit)` (which may throw
+`ios_base::failure`) [[iostate.flags]].
 ### Class template `basic_ofstream` <a id="ofstream">[[ofstream]]</a>
 ``` cpp
 namespace std {
     // [ofstream.cons], constructors
     basic_ofstream();
     explicit basic_ofstream(const char* s,
                             ios_base::openmode mode = ios_base::out);
+    explicit basic_ofstream(const filesystem::path::value_type* s,  // wide systems only; see [fstream.syn]
+                            ios_base::openmode mode = ios_base::out);
     explicit basic_ofstream(const string& s,
                             ios_base::openmode mode = ios_base::out);
     explicit basic_ofstream(const filesystem::path& s,
                             ios_base::openmode mode = ios_base::out);
+    basic_ofstream(const basic_ofstream&) = delete;
     basic_ofstream(basic_ofstream&& rhs);
     // [ofstream.assign], assign and swap
+    basic_ofstream& operator=(const basic_ofstream&) = delete;
     basic_ofstream& operator=(basic_ofstream&& rhs);
     void swap(basic_ofstream& rhs);
     // [ofstream.members], members
     basic_filebuf<charT, traits>* rdbuf() const;
 associated sequence. For the sake of exposition, the maintained data is
 presented here as:
 - `sb`, the `filebuf` object.
+#### Constructors <a id="ofstream.cons">[[ofstream.cons]]</a>
 ``` cpp
 basic_ofstream();
 ```
+*Effects:* Initializes the base class with
+`basic_ostream<charT, traits>(addressof(sb))` [[ostream.cons]] and `sb`
+with `basic_filebuf<charT, traits>()` [[filebuf.cons]].
 ``` cpp
 explicit basic_ofstream(const char* s,
                         ios_base::openmode mode = ios_base::out);
 explicit basic_ofstream(const filesystem::path::value_type* s,
                         ios_base::openmode mode = ios_base::out); // wide systems only; see [fstream.syn]
 ```
+*Effects:* Initializes the base class with
+`basic_ostream<charT, traits>(addressof(sb))` [[ostream.cons]] and `sb`
+with `basic_filebuf<charT, traits>()` [[filebuf.cons]], then calls
+`rdbuf()->open(s, mode | ios_base::out)`. If that function returns a
+null pointer, calls `setstate(failbit)`.
 ``` cpp
 explicit basic_ofstream(const string& s,
                         ios_base::openmode mode = ios_base::out);
 explicit basic_ofstream(const filesystem::path& s,
                         ios_base::openmode mode = ios_base::out);
 ```
+*Effects:* Equivalent to: `basic_ofstream(s.c_str(), mode)`.
 ``` cpp
 basic_ofstream(basic_ofstream&& rhs);
 ```
+*Effects:* Move constructs the base class, and the contained
+`basic_filebuf`. Then calls
+`basic_ostream<charT, traits>::set_rdbuf(addressof(sb))` to install the
+contained `basic_filebuf`.
+#### Assignment and swap <a id="ofstream.assign">[[ofstream.assign]]</a>
 ``` cpp
 void swap(basic_ofstream& rhs);
 ```
 template<class charT, class traits>
   void swap(basic_ofstream<charT, traits>& x,
             basic_ofstream<charT, traits>& y);
 ```
+*Effects:* Equivalent to: `x.swap(y)`.
 #### Member functions <a id="ofstream.members">[[ofstream.members]]</a>
 ``` cpp
 basic_filebuf<charT, traits>* rdbuf() const;
 ```
+*Returns:* `const_cast<basic_filebuf<charT, traits>*>(addressof(sb))`.
 ``` cpp
 bool is_open() const;
 ```
           ios_base::openmode mode = ios_base::out);             // wide systems only; see [fstream.syn]
 ```
 *Effects:* Calls `rdbuf()->open(s, mode | ios_base::out)`. If that
 function does not return a null pointer calls `clear()`, otherwise calls
+`setstate(failbit)` (which may throw
+`ios_base::failure`) [[iostate.flags]].
 ``` cpp
 void close();
 ```
 *Effects:* Calls `rdbuf()->close()` and, if that function fails (returns
 a null pointer), calls `setstate(failbit)` (which may throw
+`ios_base::failure`) [[iostate.flags]].
 ``` cpp
 void open(const string& s, ios_base::openmode mode = ios_base::out);
 void open(const filesystem::path& s, ios_base::openmode mode = ios_base::out);
 ```
     basic_fstream();
     explicit basic_fstream(
       const char* s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
     explicit basic_fstream(
+      const filesystem::path::value_type* s,
       ios_base::openmode mode = ios_base::in|ios_base::out);    // wide systems only; see [fstream.syn]
     explicit basic_fstream(
       const string& s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
     explicit basic_fstream(
       const filesystem::path& s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
+    basic_fstream(const basic_fstream&) = delete;
     basic_fstream(basic_fstream&& rhs);
     // [fstream.assign], assign and swap
+    basic_fstream& operator=(const basic_fstream&) = delete;
     basic_fstream& operator=(basic_fstream&& rhs);
     void swap(basic_fstream& rhs);
     // [fstream.members], members
     basic_filebuf<charT, traits>* rdbuf() const;
     bool is_open() const;
     void open(
       const char* s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
     void open(
+      const filesystem::path::value_type* s,
       ios_base::openmode mode = ios_base::in|ios_base::out);    // wide systems only; see [fstream.syn]
     void open(
       const string& s,
       ios_base::openmode mode = ios_base::in | ios_base::out);
     void open(
 object to control the associated sequences. For the sake of exposition,
 the maintained data is presented here as:
 - `sb`, the `basic_filebuf` object.
+#### Constructors <a id="fstream.cons">[[fstream.cons]]</a>
 ``` cpp
 basic_fstream();
 ```
+*Effects:* Initializes the base class with
+`basic_iostream<charT, traits>(addressof(sb))` [[iostream.cons]] and
 `sb` with `basic_filebuf<charT, traits>()`.
 ``` cpp
 explicit basic_fstream(
   const char* s,
 explicit basic_fstream(
   const filesystem::path::value_type* s,
   ios_base::openmode mode = ios_base::in | ios_base::out);  // wide systems only; see [fstream.syn]
 ```
+*Effects:* Initializes the base class with
+`basic_iostream<charT, traits>(addressof(sb))` [[iostream.cons]] and
 `sb` with `basic_filebuf<charT, traits>()`. Then calls
 `rdbuf()->open(s, mode)`. If that function returns a null pointer, calls
 `setstate(failbit)`.
 ``` cpp
 explicit basic_fstream(
   const filesystem::path& s,
   ios_base::openmode mode = ios_base::in | ios_base::out);
 ```
+*Effects:* Equivalent to: `basic_fstream(s.c_str(), mode)`.
 ``` cpp
 basic_fstream(basic_fstream&& rhs);
 ```
+*Effects:* Move constructs the base class, and the contained
+`basic_filebuf`. Then calls
+`basic_istream<charT, traits>::set_rdbuf(addressof(sb))` to install the
+contained `basic_filebuf`.
+#### Assignment and swap <a id="fstream.assign">[[fstream.assign]]</a>
 ``` cpp
 void swap(basic_fstream& rhs);
 ```
 template<class charT, class traits>
   void swap(basic_fstream<charT, traits>& x,
             basic_fstream<charT, traits>& y);
 ```
+*Effects:* Equivalent to: `x.swap(y)`.
 #### Member functions <a id="fstream.members">[[fstream.members]]</a>
 ``` cpp
 basic_filebuf<charT, traits>* rdbuf() const;
 ```
+*Returns:* `const_cast<basic_filebuf<charT, traits>*>(addressof(sb))`.
 ``` cpp
 bool is_open() const;
 ```
 ```
 *Effects:* Calls `rdbuf()->open(s, mode)`. If that function does not
 return a null pointer calls `clear()`, otherwise calls
 `setstate(failbit)` (which may throw
+`ios_base::failure`) [[iostate.flags]].
 ``` cpp
 void open(
   const string& s,
   ios_base::openmode mode = ios_base::in | ios_base::out);
 void close();
 ```
 *Effects:* Calls `rdbuf()->close()` and, if that function returns a null
 pointer, calls `setstate(failbit)` (which may throw
+`ios_base::failure`) [[iostate.flags]].
+## Synchronized output streams <a id="syncstream">[[syncstream]]</a>
+### Header `<syncstream>` synopsis <a id="syncstream.syn">[[syncstream.syn]]</a>
+``` cpp
+#include <ostream>  // see [ostream.syn]
+namespace std {
+  template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>
+    class basic_syncbuf;
+  using syncbuf = basic_syncbuf<char>;
+  using wsyncbuf = basic_syncbuf<wchar_t>;
+  template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>
+    class basic_osyncstream;
+  using osyncstream = basic_osyncstream<char>;
+  using wosyncstream = basic_osyncstream<wchar_t>;
+}
+```
+The header `<syncstream>` provides a mechanism to synchronize execution
+agents writing to the same stream.
+### Class template `basic_syncbuf` <a id="syncstream.syncbuf">[[syncstream.syncbuf]]</a>
+#### Overview <a id="syncstream.syncbuf.overview">[[syncstream.syncbuf.overview]]</a>
+``` cpp
+namespace std {
+  template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>
+  class basic_syncbuf : public basic_streambuf<charT, traits> {
+  public:
+    using char_type      = charT;
+    using int_type       = typename traits::int_type;
+    using pos_type       = typename traits::pos_type;
+    using off_type       = typename traits::off_type;
+    using traits_type    = traits;
+    using allocator_type = Allocator;
+    using streambuf_type = basic_streambuf<charT, traits>;
+    // [syncstream.syncbuf.cons], construction and destruction
+    basic_syncbuf()
+      : basic_syncbuf(nullptr) {}
+    explicit basic_syncbuf(streambuf_type* obuf)
+      : basic_syncbuf(obuf, Allocator()) {}
+    basic_syncbuf(streambuf_type*, const Allocator&);
+    basic_syncbuf(basic_syncbuf&&);
+    ~basic_syncbuf();
+    // [syncstream.syncbuf.assign], assignment and swap
+    basic_syncbuf& operator=(basic_syncbuf&&);
+    void swap(basic_syncbuf&);
+    // [syncstream.syncbuf.members], member functions
+    bool emit();
+    streambuf_type* get_wrapped() const noexcept;
+    allocator_type get_allocator() const noexcept;
+    void set_emit_on_sync(bool) noexcept;
+  protected:
+    // [syncstream.syncbuf.virtuals], overridden virtual functions
+    int sync() override;
+  private:
+    streambuf_type* wrapped;    // exposition only
+    bool emit_on_sync{};        // exposition only
+  };
+  // [syncstream.syncbuf.special], specialized algorithms
+  template<class charT, class traits, class Allocator>
+    void swap(basic_syncbuf<charT, traits, Allocator>&,
+              basic_syncbuf<charT, traits, Allocator>&);
+}
+```
+Class template `basic_syncbuf` stores character data written to it,
+known as the associated output, into internal buffers allocated using
+the object’s allocator. The associated output is transferred to the
+wrapped stream buffer object `*wrapped` when `emit()` is called or when
+the `basic_syncbuf` object is destroyed. Such transfers are atomic with
+respect to transfers by other `basic_syncbuf` objects with the same
+wrapped stream buffer object.
+#### Construction and destruction <a id="syncstream.syncbuf.cons">[[syncstream.syncbuf.cons]]</a>
+``` cpp
+basic_syncbuf(streambuf_type* obuf, const Allocator& allocator);
+```
+*Effects:* Sets `wrapped` to `obuf`.
+*Remarks:* A copy of `allocator` is used to allocate memory for internal
+buffers holding the associated output.
+*Throws:* Nothing unless an exception is thrown by the construction of a
+mutex or by memory allocation.
+*Ensures:* `get_wrapped() == obuf` and `get_allocator() == allocator`
+are `true`.
+``` cpp
+basic_syncbuf(basic_syncbuf&& other);
+```
+*Ensures:* The value returned by `this->get_wrapped()` is the value
+returned by `other.get_wrapped()` prior to calling this constructor.
+Output stored in `other` prior to calling this constructor will be
+stored in `*this` afterwards.
+`other.rdbuf()->pbase() == other.rdbuf()->pptr()` and
+`other.get_wrapped() == nullptr` are `true`.
+*Remarks:* This constructor disassociates `other` from its wrapped
+stream buffer, ensuring destruction of `other` produces no output.
+``` cpp
+~basic_syncbuf();
+```
+*Effects:* Calls `emit()`.
+*Throws:* Nothing. If an exception is thrown from `emit()`, the
+destructor catches and ignores that exception.
+#### Assignment and swap <a id="syncstream.syncbuf.assign">[[syncstream.syncbuf.assign]]</a>
+``` cpp
+basic_syncbuf& operator=(basic_syncbuf&& rhs) noexcept;
+```
+*Effects:* Calls `emit()` then move assigns from `rhs`. After the move
+assignment `*this` has the observable state it would have had if it had
+been move constructed from `rhs` [[syncstream.syncbuf.cons]].
+*Returns:* `*this`.
+*Ensures:*
+- `rhs.get_wrapped() == nullptr` is `true`.
+- `this->get_allocator() == rhs.get_allocator()` is `true` when
+  ``` cpp
+  allocator_traits<Allocator>::propagate_on_container_move_assignment::value
+  ```
+  is `true`; otherwise, the allocator is unchanged.
+*Remarks:* This assignment operator disassociates `rhs` from its wrapped
+stream buffer, ensuring destruction of `rhs` produces no output.
+``` cpp
+void swap(basic_syncbuf& other) noexcept;
+```
+*Preconditions:* Either
+`allocator_traits<Allocator>::propagate_on_container_swap::value` is
+`true` or `this->get_allocator() == other.get_allocator()` is `true`.
+*Effects:* Exchanges the state of `*this` and `other`.
+#### Member functions <a id="syncstream.syncbuf.members">[[syncstream.syncbuf.members]]</a>
+``` cpp
+bool emit();
+```
+*Effects:* Atomically transfers the associated output of `*this` to the
+stream buffer `*wrapped`, so that it appears in the output stream as a
+contiguous sequence of characters. `wrapped->pubsync()` is called if and
+only if a call was made to `sync()` since the most recent call to
+`emit()`, if any.
+*Returns:* `true` if all of the following conditions hold; otherwise
+`false`:
+- `wrapped == nullptr` is `false`.
+- All of the characters in the associated output were successfully
+  transferred.
+- The call to `wrapped->pubsync()` (if any) succeeded.
+*Ensures:* On success, the associated output is empty.
+*Synchronization:* All `emit()` calls transferring characters to the
+same stream buffer object appear to execute in a total order consistent
+with the “happens before” relation [[intro.races]], where each `emit()`
+call synchronizes with subsequent `emit()` calls in that total order.
+*Remarks:* May call member functions of `wrapped` while holding a lock
+uniquely associated with `wrapped`.
+``` cpp
+streambuf_type* get_wrapped() const noexcept;
+```
+*Returns:* `wrapped`.
+``` cpp
+allocator_type get_allocator() const noexcept;
+```
+*Returns:* A copy of the allocator that was set in the constructor or
+assignment operator.
+``` cpp
+void set_emit_on_sync(bool b) noexcept;
+```
+*Effects:* `emit_on_sync = b`.
+#### Overridden virtual functions <a id="syncstream.syncbuf.virtuals">[[syncstream.syncbuf.virtuals]]</a>
+``` cpp
+int sync() override;
+```
+*Effects:* Records that the wrapped stream buffer is to be flushed.
+Then, if `emit_on_sync` is `true`, calls `emit()`.
+[*Note 1*: If `emit_on_sync` is `false`, the actual flush is delayed
+until a call to `emit()`. — *end note*]
+*Returns:* If `emit()` was called and returned `false`, returns `-1`;
+otherwise `0`.
+#### Specialized algorithms <a id="syncstream.syncbuf.special">[[syncstream.syncbuf.special]]</a>
+``` cpp
+template<class charT, class traits, class Allocator>
+  void swap(basic_syncbuf<charT, traits, Allocator>& a,
+            basic_syncbuf<charT, traits, Allocator>& b) noexcept;
+```
+*Effects:* Equivalent to `a.swap(b)`.
+### Class template `basic_osyncstream` <a id="syncstream.osyncstream">[[syncstream.osyncstream]]</a>
+#### Overview <a id="syncstream.osyncstream.overview">[[syncstream.osyncstream.overview]]</a>
+``` cpp
+namespace std {
+  template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>
+  class basic_osyncstream : public basic_ostream<charT, traits> {
+  public:
+    using char_type   = charT;
+    using int_type    = typename traits::int_type;
+    using pos_type    = typename traits::pos_type;
+    using off_type    = typename traits::off_type;
+    using traits_type = traits;
+    using allocator_type = Allocator;
+    using streambuf_type = basic_streambuf<charT, traits>;
+    using syncbuf_type   = basic_syncbuf<charT, traits, Allocator>;
+    // [syncstream.osyncstream.cons], construction and destruction
+    basic_osyncstream(streambuf_type*, const Allocator&);
+    explicit basic_osyncstream(streambuf_type* obuf)
+      : basic_osyncstream(obuf, Allocator()) {}
+    basic_osyncstream(basic_ostream<charT, traits>& os, const Allocator& allocator)
+      : basic_osyncstream(os.rdbuf(), allocator) {}
+    explicit basic_osyncstream(basic_ostream<charT, traits>& os)
+      : basic_osyncstream(os, Allocator()) {}
+    basic_osyncstream(basic_osyncstream&&) noexcept;
+    ~basic_osyncstream();
+    // assignment
+    basic_osyncstream& operator=(basic_osyncstream&&) noexcept;
+    // [syncstream.osyncstream.members], member functions
+    void emit();
+    streambuf_type* get_wrapped() const noexcept;
+    syncbuf_type* rdbuf() const noexcept { return const_cast<syncbuf_type*>(addressof(sb)); }
+  private:
+    syncbuf_type sb;    // exposition only
+  };
+}
+```
+`Allocator` shall meet the *Cpp17Allocator* requirements (
+[[cpp17.allocator]]).
+[*Example 1*:
+A named variable can be used within a block statement for streaming.
+``` cpp
+{
+  osyncstream bout(cout);
+  bout << "Hello, ";
+  bout << "World!";
+  bout << endl; // flush is noted
+  bout << "and more!\n";
+}   // characters are transferred and cout is flushed
+```
+— *end example*]
+[*Example 2*:
+A temporary object can be used for streaming within a single statement.
+``` cpp
+osyncstream(cout) << "Hello, " << "World!" << '\n';
+```
+In this example, `cout` is not flushed.
+— *end example*]
+#### Construction and destruction <a id="syncstream.osyncstream.cons">[[syncstream.osyncstream.cons]]</a>
+``` cpp
+basic_osyncstream(streambuf_type* buf, const Allocator& allocator);
+```
+*Effects:* Initializes `sb` from `buf` and `allocator`. Initializes the
+base class with `basic_ostream<charT, traits>(addressof(sb))`.
+[*Note 1*: The member functions of the provided stream buffer might be
+called from `emit()` while a lock is held. Care should be taken to
+ensure that this does not result in deadlock. — *end note*]
+*Ensures:* `get_wrapped() == buf` is `true`.
+``` cpp
+basic_osyncstream(basic_osyncstream&& other) noexcept;
+```
+*Effects:* Move constructs the base class and `sb` from the
+corresponding subobjects of `other`, and calls
+`basic_ostream<charT, traits>::set_rdbuf(addressof(sb))`.
+*Ensures:* The value returned by `get_wrapped()` is the value returned
+by `os.get_wrapped()` prior to calling this constructor.
+`nullptr == other.get_wrapped()` is `true`.
+#### Member functions <a id="syncstream.osyncstream.members">[[syncstream.osyncstream.members]]</a>
+``` cpp
+void emit();
+```
+*Effects:* Calls `sb.emit()`. If that call returns `false`, calls
+`setstate(ios_base::badbit)`.
+[*Example 1*:
+A flush on a `basic_osyncstream` does not flush immediately:
+``` cpp
+{
+  osyncstream bout(cout);
+  bout << "Hello," << '\n';     // no flush
+  bout.emit();                  // characters transferred; cout not flushed
+  bout << "World!" << endl;     // flush noted; cout not flushed
+  bout.emit();                  // characters transferred; cout flushed
+  bout << "Greetings." << '\n'; // no flush
+}   // characters transferred; cout not flushed
+```
+— *end example*]
+[*Example 2*:
+The function `emit()` can be used to handle exceptions from operations
+on the underlying stream.
+``` cpp
+{
+  osyncstream bout(cout);
+  bout << "Hello, " << "World!" << '\n';
+  try {
+    bout.emit();
+  } catch (...) {
+    // handle exception
+  }
+}
+```
+— *end example*]
+``` cpp
+streambuf_type* get_wrapped() const noexcept;
+```
+*Returns:* `sb.get_wrapped()`.
+[*Example 3*:
+Obtaining the wrapped stream buffer with `get_wrapped()` allows wrapping
+it again with an `osyncstream`. For example,
+``` cpp
+{
+  osyncstream bout1(cout);
+  bout1 << "Hello, ";
+  {
+    osyncstream(bout1.get_wrapped()) << "Goodbye, " << "Planet!" << '\n';
+  }
+  bout1 << "World!" << '\n';
+}
+```
+produces the *uninterleaved* output
+``` text
+Goodbye, Planet!
+Hello, World!
+```
+— *end example*]
 ## File systems <a id="filesystems">[[filesystems]]</a>
 ### General <a id="fs.general">[[fs.general]]</a>
+Subclause  [[filesystems]] describes operations on file systems and
+their components, such as paths, regular files, and directories.
+A *file system* is a collection of files and their attributes.
+A *file* is an object within a file system that holds user or system
+data. Files can be written to, or read from, or both. A file has certain
+attributes, including type. File types include regular files and
+directories. Other types of files, such as symbolic links, may be
+supported by the implementation.
+A *directory* is a file within a file system that acts as a container of
+directory entries that contain information about other files, possibly
+including other directory files. The *parent directory* of a directory
+is the directory that both contains a directory entry for the given
+directory and is represented by the dot-dot filename [[fs.path.generic]]
+in the given directory. The *parent directory* of other types of files
+is a directory containing a directory entry for the file under
+discussion.
+A *link* is an object that associates a filename with a file. Several
+links can associate names with the same file. A *hard link* is a link to
+an existing file. Some file systems support multiple hard links to a
+file. If the last hard link to a file is removed, the file itself is
+removed.
+[*Note 1*: A hard link can be thought of as a shared-ownership smart
+pointer to a file. — *end note*]
+A *symbolic link* is a type of file with the property that when the file
+is encountered during pathname resolution [[fs.class.path]], a string
+stored by the file is used to modify the pathname resolution.
+[*Note 2*: Symbolic links are often called symlinks. A symbolic link
+can be thought of as a raw pointer to a file. If the file pointed to
+does not exist, the symbolic link is said to be a “dangling” symbolic
+link. — *end note*]
 ### Conformance <a id="fs.conformance">[[fs.conformance]]</a>
 Conformance is specified in terms of behavior. Ideal behavior is not
 always implementable, so the conformance subclauses take that into
 account.
 #### POSIX conformance <a id="fs.conform.9945">[[fs.conform.9945]]</a>
+Some behavior is specified by reference to POSIX [[fs.norm.ref]]. How
 such behavior is actually implemented is unspecified.
 [*Note 1*: This constitutes an “as if” rule allowing implementations to
 call native operating system or other APIs. — *end note*]
+Implementations should provide such behavior as it is defined by POSIX.
+Implementations shall document any behavior that differs from the
+behavior defined by POSIX. Implementations that do not support exact
+POSIX behavior should provide behavior as close to POSIX behavior as is
+reasonable given the limitations of actual operating systems and file
+systems. If an implementation cannot provide any reasonable behavior,
+the implementation shall report an error as specified in
+[[fs.err.report]].
 [*Note 2*: This allows users to rely on an exception being thrown or an
 error code being set when an implementation cannot provide any
 reasonable behavior. — *end note*]
 required to support those features on the FAT file system but instead
 are required to report an error as described above. — *end example*]
 #### Operating system dependent behavior conformance <a id="fs.conform.os">[[fs.conform.os]]</a>
+Behavior that is specified as being *operating system dependent* is
+dependent upon the behavior and characteristics of an operating system.
+The operating system an implementation is dependent upon is
+*implementation-defined*.
 It is permissible for an implementation to be dependent upon an
 operating system emulator rather than the actual underlying operating
 system.
 #### File system race behavior <a id="fs.race.behavior">[[fs.race.behavior]]</a>
+A *file system race* is the condition that occurs when multiple threads,
+processes, or computers interleave access and modification of the same
+object within a file system. Behavior is undefined if calls to functions
+provided by subclause  [[fs.race.behavior]] introduce a file system
+race.
 If the possibility of a file system race would make it unreliable for a
 program to test for a precondition before calling a function described
+herein, *Preconditions:* is not specified for the function.
 [*Note 1*: As a design practice, preconditions are not specified when
 it is unreasonable for a program to detect them prior to calling the
 function. — *end note*]
 ### Normative references <a id="fs.norm.ref">[[fs.norm.ref]]</a>
+Subclause  [[filesystems]] mentions commercially available operating
+systems for purposes of exposition.[^41]
 ### Requirements <a id="fs.req">[[fs.req]]</a>
+Throughout subclause  [[filesystems]], `char`, `wchar_t`, `char8_t`,
+`char16_t`, and `char32_t` are collectively called *encoded character
+types*.
 Functions with template parameters named `EcharT` shall not participate
 in overload resolution unless `EcharT` is one of the encoded character
 types.
+Template parameters named `InputIterator` shall meet the
+*Cpp17InputIterator* requirements [[input.iterators]] and shall have a
+value type that is one of the encoded character types.
 [*Note 1*: Use of an encoded character type implies an associated
 character set and encoding. Since `signed char` and `unsigned char` have
 no implied character set and encoding, they are not included as
 permitted types. — *end note*]
+Template parameters named `Allocator` shall meet the *Cpp17Allocator*
+requirements ([[cpp17.allocator]]).
 #### Namespaces and headers <a id="fs.req.namespace">[[fs.req.namespace]]</a>
+Unless otherwise specified, references to entities described in
+subclause  [[filesystems]] are assumed to be qualified with
+`::std::filesystem::`.
 ### Header `<filesystem>` synopsis <a id="fs.filesystem.syn">[[fs.filesystem.syn]]</a>
 ``` cpp
+#include <compare>              // see [compare.syn]
 namespace std::filesystem {
   // [fs.class.path], paths
   class path;
   // [fs.path.nonmember], path non-member functions
   void swap(path& lhs, path& rhs) noexcept;
   size_t hash_value(const path& p) noexcept;
+ // [fs.class.filesystem.error], filesystem errors
   class filesystem_error;
+  // [fs.class.directory.entry], directory entries
   class directory_entry;
+  // [fs.class.directory.iterator], directory iterators
   class directory_iterator;
   // [fs.dir.itr.nonmembers], range access for directory iterators
   directory_iterator begin(directory_iterator iter) noexcept;
   directory_iterator end(const directory_iterator&) noexcept;
   // [fs.rec.dir.itr.nonmembers], range access for recursive directory iterators
   recursive_directory_iterator begin(recursive_directory_iterator iter) noexcept;
   recursive_directory_iterator end(const recursive_directory_iterator&) noexcept;
+  // [fs.class.file.status], file status
   class file_status;
   struct space_info {
     uintmax_t capacity;
     uintmax_t free;
     uintmax_t available;
+    friend bool operator==(const space_info&, const space_info&) = default;
   };
   // [fs.enum], enumerations
   enum class file_type;
   enum class perms;
   enum class perm_options;
   enum class copy_options;
   enum class directory_options;
+  using file_time_type = chrono::time_point<chrono::file_clock>;
   // [fs.op.funcs], filesystem operations
+  path absolute(const path& p);
+  path absolute(const path& p, error_code& ec);
+  path canonical(const path& p);
   path canonical(const path& p, error_code& ec);
   void copy(const path& from, const path& to);
+  void copy(const path& from, const path& to, error_code& ec);
   void copy(const path& from, const path& to, copy_options options);
   void copy(const path& from, const path& to, copy_options options,
+            error_code& ec);
   bool copy_file(const path& from, const path& to);
+  bool copy_file(const path& from, const path& to, error_code& ec);
   bool copy_file(const path& from, const path& to, copy_options option);
   bool copy_file(const path& from, const path& to, copy_options option,
+                 error_code& ec);
   void copy_symlink(const path& existing_symlink, const path& new_symlink);
   void copy_symlink(const path& existing_symlink, const path& new_symlink,
                     error_code& ec) noexcept;
   bool create_directories(const path& p);
+  bool create_directories(const path& p, error_code& ec);
   bool create_directory(const path& p);
   bool create_directory(const path& p, error_code& ec) noexcept;
   bool create_directory(const path& p, const path& attributes);
   path current_path();
   path current_path(error_code& ec);
   void current_path(const path& p);
   void current_path(const path& p, error_code& ec) noexcept;
+  bool equivalent(const path& p1, const path& p2);
+  bool equivalent(const path& p1, const path& p2, error_code& ec) noexcept;
   bool exists(file_status s) noexcept;
   bool exists(const path& p);
   bool exists(const path& p, error_code& ec) noexcept;
   uintmax_t file_size(const path& p);
   uintmax_t file_size(const path& p, error_code& ec) noexcept;
   uintmax_t hard_link_count(const path& p);
   uintmax_t hard_link_count(const path& p, error_code& ec) noexcept;
   bool is_directory(file_status s) noexcept;
   bool is_directory(const path& p);
   bool is_directory(const path& p, error_code& ec) noexcept;
   bool is_empty(const path& p);
+  bool is_empty(const path& p, error_code& ec);
   bool is_fifo(file_status s) noexcept;
   bool is_fifo(const path& p);
   bool is_fifo(const path& p, error_code& ec) noexcept;
   bool remove(const path& p);
   bool remove(const path& p, error_code& ec) noexcept;
   uintmax_t remove_all(const path& p);
+  uintmax_t remove_all(const path& p, error_code& ec);
   void rename(const path& from, const path& to);
   void rename(const path& from, const path& to, error_code& ec) noexcept;
   void resize_file(const path& p, uintmax_t size);
   path weakly_canonical(const path& p);
   path weakly_canonical(const path& p, error_code& ec);
 }
 ```
+Implementations should ensure that the resolution and range of
+`file_time_type` reflect the operating system dependent resolution and
+range of file time values.
 ### Error reporting <a id="fs.err.report">[[fs.err.report]]</a>
 Filesystem library functions often provide two overloads, one that
 throws an exception to report file system errors, and another that sets
   appropriate for the specific operating system dependent error.
   Otherwise, `clear()` is called on the `error_code&` argument.
 ### Class `path` <a id="fs.class.path">[[fs.class.path]]</a>
+An object of class `path` represents a path and contains a pathname.
+Such an object is concerned only with the lexical and syntactic aspects
+of a path. The path does not necessarily exist in external storage, and
+the pathname is not necessarily valid for the current operating system
+or for a particular file system.
 [*Note 1*: Class `path` is used to support the differences between the
 string types used by different operating systems to represent pathnames,
 and to perform conversions between encodings when
 necessary. — *end note*]
+A *path* is a sequence of elements that identify the location of a file
+within a filesystem. The elements are the *root-name*ₒₚₜ ,
+*root-directory*ₒₚₜ , and an optional sequence of *filename*s
+[[fs.path.generic]]. The maximum number of elements in the sequence is
+operating system dependent [[fs.conform.os]].
+An *absolute path* is a path that unambiguously identifies the location
+of a file without reference to an additional starting location. The
+elements of a path that determine if it is absolute are operating system
+dependent. A *relative path* is a path that is not absolute, and as
+such, only unambiguously identifies the location of a file when resolved
+relative to an implied starting location. The elements of a path that
+determine if it is relative are operating system dependent.
+[*Note 2*: Pathnames “.” and “..” are relative paths. — *end note*]
+A *pathname* is a character string that represents the name of a path.
+Pathnames are formatted according to the generic pathname format grammar
+[[fs.path.generic]] or according to an operating system dependent
+*native pathname format* accepted by the host operating system.
+*Pathname resolution* is the operating system dependent mechanism for
+resolving a pathname to a particular file in a file hierarchy. There may
+be multiple pathnames that resolve to the same file.
+[*Example 1*: POSIX specifies the mechanism in section 4.11, Pathname
+resolution. — *end example*]
 ``` cpp
 namespace std::filesystem {
   class path {
   public:
     using value_type  = see below;
     path& operator=(string_type&& source);
     path& assign(string_type&& source);
     template<class Source>
       path& operator=(const Source& source);
     template<class Source>
+      path& assign(const Source& source);
     template<class InputIterator>
       path& assign(InputIterator first, InputIterator last);
     // [fs.path.append], appends
     path& operator/=(const path& p);
     path& remove_filename();
     path& replace_filename(const path& replacement);
     path& replace_extension(const path& replacement = path());
     void  swap(path& rhs) noexcept;
+    // [fs.path.nonmember], non-member operators
+    friend bool operator==(const path& lhs, const path& rhs) noexcept;
+    friend strong_ordering operator<=>(const path& lhs, const path& rhs) noexcept;
+    friend path operator/ (const path& lhs, const path& rhs);
     // [fs.path.native.obs], native format observers
     const string_type& native() const noexcept;
     const value_type*  c_str() const noexcept;
     operator string_type() const;
              class Allocator = allocator<EcharT>>
       basic_string<EcharT, traits, Allocator>
         string(const Allocator& a = Allocator()) const;
     std::string    string() const;
     std::wstring   wstring() const;
+    std::u8string  u8string() const;
     std::u16string u16string() const;
     std::u32string u32string() const;
     // [fs.path.generic.obs], generic format observers
     template<class EcharT, class traits = char_traits<EcharT>,
              class Allocator = allocator<EcharT>>
       basic_string<EcharT, traits, Allocator>
         generic_string(const Allocator& a = Allocator()) const;
     std::string    generic_string() const;
     std::wstring   generic_wstring() const;
+    std::u8string  generic_u8string() const;
     std::u16string generic_u16string() const;
     std::u32string generic_u32string() const;
     // [fs.path.compare], compare
     int compare(const path& p) const noexcept;
     path filename() const;
     path stem() const;
     path extension() const;
     // [fs.path.query], query
+ [[nodiscard]] bool empty() const noexcept;
     bool has_root_name() const;
     bool has_root_directory() const;
     bool has_root_path() const;
     bool has_relative_path() const;
     bool has_parent_path() const;
     class iterator;
     using const_iterator = iterator;
     iterator begin() const;
     iterator end() const;
+    // [fs.path.io], path inserter and extractor
+    template<class charT, class traits>
+      friend basic_ostream<charT, traits>&
+        operator<<(basic_ostream<charT, traits>& os, const path& p);
+    template<class charT, class traits>
+      friend basic_istream<charT, traits>&
+        operator>>(basic_istream<charT, traits>& is, path& p);
   };
 }
 ```
 `value_type` is a `typedef` for the operating system dependent encoded
 character type used to represent pathnames.
 The value of the `preferred_separator` member is the operating system
+dependent *preferred-separator* character [[fs.path.generic]].
+[*Example 2*: For POSIX-based operating systems, `value_type` is `char`
 and `preferred_separator` is the slash character (`'/'`). For
 Windows-based operating systems, `value_type` is `wchar_t` and
 `preferred_separator` is the backslash character
 (`L'\\'`). — *end example*]
 ``` bnf
 fallback-separator:
     /, if *preferred-separator* is not /
 ```
+A *filename* is the name of a file. The *dot* and *dot-dot* filenames,
+consisting solely of one and two period characters respectively, have
+special meaning. The following characteristics of filenames are
+operating system dependent:
+- The permitted characters. \[*Example 1*: Some operating systems
+  prohibit the ASCII control characters (0x00 – 0x1F) in
+  filenames. — *end example*] \[*Note 1*: For wide portability, users
+  may wish to limit *filename* characters to the POSIX Portable Filename
+  Character Set:
   `A B C D E F G H I J K L M N O P Q R S T U V W X Y Z`
   `a b c d e f g h i j k l m n o p q r s t u v w x y z`
   `0 1 2 3 4 5 6 7 8 9 . _ -` — *end note*]
+- The maximum permitted length.
+- Filenames that are not permitted.
+- Filenames that have special meaning.
+- Case awareness and sensitivity during path resolution.
+- Special rules that may apply to file types other than regular files,
+  such as directories.
 Except in a *root-name*, multiple successive *directory-separator*
 characters are considered to be the same as one *directory-separator*
 character.
+The dot filename is treated as a reference to the current directory. The
+dot-dot filename is treated as a reference to the parent directory. What
+the dot-dot filename refers to relative to *root-directory* is
 *implementation-defined*. Specific filenames may have special meanings
 for a particular operating system.
+A *root-name* identifies the starting location for pathname resolution
+[[fs.class.path]]. If there are no operating system dependent
 *root-name*s, at least one *implementation-defined* *root-name* is
 required.
 [*Note 2*: Many operating systems define a name beginning with two
 *directory-separator* characters as a *root-name* that identifies
 [*Note 3*: On a POSIX-like operating system, it is impossible to have a
 *root-name* and a *relative-path* without an intervening
 *root-directory* element. — *end note*]
+*Normalization* of a generic format pathname means:
+1.  If the path is empty, stop.
+2.  Replace each slash character in the *root-name* with a
+    *preferred-separator*.
+3.  Replace each *directory-separator* with a *preferred-separator*.
+    \[*Note 4*: The generic pathname grammar [[fs.path.generic]] defines
+    *directory-separator* as one or more slashes and
+    *preferred-separator*s. — *end note*]
+4.  Remove each dot filename and any immediately following
+    *directory-separator*.
+5.  As long as any appear, remove a non-dot-dot filename immediately
+    followed by a *directory-separator* and a dot-dot filename, along
+    with any immediately following *directory-separator*.
+6.  If there is a *root-directory*, remove all dot-dot filenames and any
+    *directory-separator*s immediately following them. \[*Note 5*: These
+    dot-dot filenames attempt to refer to nonexistent parent
+    directories. — *end note*]
+7.  If the last filename is dot-dot, remove any trailing
+    *directory-separator*.
+8.  If the path is empty, add a dot.
+The result of normalization is a path in *normal form*, which is said to
+be *normalized*.
+#### Conversions <a id="fs.path.cvt">[[fs.path.cvt]]</a>
+##### Argument format conversions <a id="fs.path.fmt.cvt">[[fs.path.fmt.cvt]]</a>
 [*Note 1*:
+The format conversions described in this subclause are not applied on
 POSIX-based operating systems because on these systems:
 - The generic format is acceptable as a native path.
 - There is no need to distinguish between native format and generic
   format in function arguments.
 — *end note*]
 Several functions are defined to accept *detected-format* arguments,
 which are character sequences. A detected-format argument represents a
+path using either a pathname in the generic format [[fs.path.generic]]
+or a pathname in the native format [[fs.class.path]]. Such an argument
+is taken to be in the generic format if and only if it matches the
+generic format and is not acceptable to the operating system as a native
+path.
 [*Note 2*: Some operating systems may have no unambiguous way to
 distinguish between native format and generic format arguments. This is
 by design as it simplifies use for operating systems that do not require
 disambiguation. An implementation for an operating system where
 If the native format requires paths for regular files to be formatted
 differently from paths for directories, the path shall be treated as a
 directory path if its last element is a *directory-separator*, otherwise
 it shall be treated as a path to a regular file.
+[*Note 4*: A path stores a native format pathname
+[[fs.path.native.obs]] and acts as if it also stores a generic format
 pathname, related as given below. The implementation may generate the
 generic format pathname based on the native format pathname (and
 possibly other information) when requested. — *end note*]
 When a path is constructed from or is assigned a single representation
 as appropriate) if any such value does so; *q* is otherwise unspecified.
 [*Note 5*: If *q* is the result of converting any path at all, it is
 the result of converting *p*. — *end note*]
+##### Type and encoding conversions <a id="fs.path.type.cvt">[[fs.path.type.cvt]]</a>
+The *native encoding* of an ordinary character string is the operating
+system dependent current encoding for pathnames [[fs.class.path]]. The
+*native encoding* for wide character strings is the
+implementation-defined execution wide-character set encoding
+[[lex.charset]].
 For member function arguments that take character sequences representing
 paths and for member functions returning strings, value type and
 encoding conversion is performed if the value type of the argument or
 return value differs from `path::value_type`. For the argument or return
 value, the method of conversion and the encoding to be converted to is
 determined by its value type:
+- `char`: The encoding is the native ordinary encoding. The method of
+  conversion, if any, is operating system dependent. \[*Note 6*: For
+ POSIX-based operating systems `path::value_type` is `char` so no
+ conversion from `char` value type arguments or to `char` value type
+ return values is performed. For Windows-based operating systems, the
+ native ordinary encoding is determined by calling a Windows API
   function. — *end note*] \[*Note 7*: This results in behavior
   identical to other C and C++ standard library functions that perform
+  file operations using ordinary character strings to identify paths.
   Changing this behavior would be surprising and error
   prone. — *end note*]
+- `wchar_t`: The encoding is the native wide encoding. The method of
+  conversion is unspecified. \[*Note 8*: For Windows-based operating
+  systems `path::value_type` is `wchar_t` so no conversion from
+  `wchar_t` value type arguments or to `wchar_t` value type return
+  values is performed. — *end note*]
+- `char8_t`: The encoding is UTF-8. The method of conversion is
+  unspecified.
 - `char16_t`: The encoding is UTF-16. The method of conversion is
   unspecified.
 - `char32_t`: The encoding is UTF-32. The method of conversion is
   unspecified.
 If the encoding being converted to has no representation for source
 characters, the resulting converted characters, if any, are unspecified.
 Implementations should not modify member function arguments if already
 of type `path::value_type`.
+#### Requirements <a id="fs.path.req">[[fs.path.req]]</a>
+In addition to the requirements [[fs.req]], function template parameters
+named `Source` shall be one of:
 - `basic_string<EcharT, traits, Allocator>`. A function argument
   `const Source&` `source` shall have an effective range
   \[`source.begin()`, `source.end()`).
 - `basic_string_view<EcharT, traits>`. A function argument
   `const Source&` `source` shall have an effective range
   \[`source.begin()`, `source.end()`).
+- A type meeting the *Cpp17InputIterator* requirements that iterates
+ over a NTCTS. The value type shall be an encoded character type. A
+ function argument `const Source&` `source` shall have an effective
+ range \[`source`, `end`) where `end` is the first iterator value with
+ an element value equal to `iterator_traits<Source>::value_type()`.
 - A character array that after array-to-pointer decay results in a
   pointer to the start of a NTCTS. The value type shall be an encoded
   character type. A function argument `const Source&` `source` shall
   have an effective range \[`source`, `end`) where `end` is the first
   iterator value with an element value equal to
   `iterator_traits<decay_t<Source>>::value_type()`.
 Functions taking template parameters named `Source` shall not
+participate in overload resolution unless `Source` denotes a type other
+than `path`, and either
 - `Source` is a specialization of `basic_string` or `basic_string_view`,
   or
 - the *qualified-id* `iterator_traits<decay_t<Source>>::value_type` is
+  valid and denotes a possibly `const` encoded character type
+  [[temp.deduct]].
+[*Note 1*: See path conversions [[fs.path.cvt]] for how the value types
+above and their encodings convert to `path::value_type` and its
 encoding. — *end note*]
 Arguments of type `Source` shall not be null pointers.
+#### Members <a id="fs.path.member">[[fs.path.member]]</a>
+##### Constructors <a id="fs.path.construct">[[fs.path.construct]]</a>
 ``` cpp
 path() noexcept;
 ```
+*Ensures:* `empty() == true`.
 ``` cpp
 path(const path& p);
 path(path&& p) noexcept;
 ```
 ``` cpp
 path(string_type&& source, format fmt = auto_format);
 ```
 *Effects:* Constructs an object of class `path` for which the pathname
+in the detected-format of `source` has the original value of `source`
+[[fs.path.fmt.cvt]], converting format if required [[fs.path.fmt.cvt]].
+`source` is left in a valid but unspecified state.
 ``` cpp
 template<class Source>
   path(const Source& source, format fmt = auto_format);
 template<class InputIterator>
   path(InputIterator first, InputIterator last, format fmt = auto_format);
 ```
+*Effects:* Let `s` be the effective range of `source` [[fs.path.req]] or
+the range \[`first`, `last`), with the encoding converted if
+required [[fs.path.cvt]]. Finds the detected-format of `s`
+[[fs.path.fmt.cvt]] and constructs an object of class `path` for which
+the pathname in that format is `s`.
 ``` cpp
 template<class Source>
   path(const Source& source, const locale& loc, format fmt = auto_format);
 template<class InputIterator>
   path(InputIterator first, InputIterator last, const locale& loc, format fmt = auto_format);
 ```
+*Mandates:* The value type of `Source` and `InputIterator` is `char`.
 *Effects:* Let `s` be the effective range of `source` or the range
 \[`first`, `last`), after converting the encoding as follows:
 - If `value_type` is `wchar_t`, converts to the native wide
+  encoding [[fs.path.type.cvt]] using the
   `codecvt<wchar_t, char, mbstate_t>` facet of `loc`.
 - Otherwise a conversion is performed using the
   `codecvt<wchar_t, char, mbstate_t>` facet of `loc`, and then a second
+  conversion to the current ordinary encoding.
+Finds the detected-format of `s` [[fs.path.fmt.cvt]] and constructs an
+object of class `path` for which the pathname in that format is `s`.
 [*Example 1*:
 A string is to be read from a database that is encoded in ISO/IEC
 8859-1, and used to create a directory:
 ```
 For POSIX-based operating systems, the path is constructed by first
 using `latin1_facet` to convert ISO/IEC 8859-1 encoded `latin1_string`
 to a wide character string in the native wide
+encoding [[fs.path.type.cvt]]. The resulting wide string is then
+converted to an ordinary character pathname string in the current native
+ordinary encoding. If the native wide encoding is UTF-16 or UTF-32, and
+the current native ordinary encoding is UTF-8, all of the characters in
 the ISO/IEC 8859-1 character set will be converted to their Unicode
+representation, but for other native ordinary encodings some characters
 may have no representation.
 For Windows-based operating systems, the path is constructed by using
 `latin1_facet` to convert ISO/IEC 8859-1 encoded `latin1_string` to a
 UTF-16 encoded wide character pathname string. All of the characters in
 the ISO/IEC 8859-1 character set will be converted to their Unicode
 representation.
 — *end example*]
+##### Assignments <a id="fs.path.assign">[[fs.path.assign]]</a>
 ``` cpp
 path& operator=(const path& p);
 ```
   path& assign(const Source& source);
 template<class InputIterator>
   path& assign(InputIterator first, InputIterator last);
 ```
+*Effects:* Let `s` be the effective range of `source` [[fs.path.req]] or
+the range \[`first`, `last`), with the encoding converted if
+required [[fs.path.cvt]]. Finds the detected-format of `s`
+[[fs.path.fmt.cvt]] and sets the pathname in that format to `s`.
 *Returns:* `*this`.
+##### Appends <a id="fs.path.append">[[fs.path.append]]</a>
 The append operations use `operator/=` to denote their semantic effect
 of appending *preferred-separator* when needed.
 ``` cpp
   pathname.
 [*Example 2*:
 Even if `//host` is interpreted as a *root-name*, both of the paths
+`path("//host")/"foo"` and `path("//host/")/"foo"` equal `"//host/foo"`
+(although the former might use backslash as the preferred separator).
 Expression examples:
 ``` cpp
 // On POSIX,
+path("foo") /= path(""); // yields path("foo/")
+path("foo") /= path("/bar"); // yields path("/bar")
 // On Windows,
+path("foo") /= path(""); // yields path("foo\{")}
+path("foo") /= path("/bar"); // yields path("/bar")
+path("foo") /= path("c:/bar"); // yields path("c:/bar")
+path("foo") /= path("c:"); // yields path("c:")
+path("c:") /= path(""); // yields path("c:")
+path("c:foo") /= path("/bar");  // yields path("c:/bar")
+path("c:foo") /= path("c:bar"); // yields path("c:foo\{bar")}
 ```
 — *end example*]
 *Returns:* `*this`.
   path& append(InputIterator first, InputIterator last);
 ```
 *Effects:* Equivalent to: `return operator/=(path(first, last));`
+##### Concatenation <a id="fs.path.concat">[[fs.path.concat]]</a>
 ``` cpp
 path& operator+=(const path& x);
 path& operator+=(const string_type& x);
 path& operator+=(basic_string_view<value_type> x);
 path& operator+=(const value_type* x);
 template<class Source>
   path& operator+=(const Source& x);
 template<class Source>
   path& concat(const Source& x);
 ```
 *Effects:* Appends `path(x).native()` to the pathname in the native
 [*Note 2*: This directly manipulates the value of `native()` and may
 not be portable between operating systems. — *end note*]
 *Returns:* `*this`.
+``` cpp
+path& operator+=(value_type x);
+template<class EcharT>
+  path& operator+=(EcharT x);
+```
+*Effects:* Equivalent to: `return *this += basic_string_view(&x, 1);`
 ``` cpp
 template<class InputIterator>
   path& concat(InputIterator first, InputIterator last);
 ```
+*Effects:* Equivalent to: `return *this += path(first, last);`
+##### Modifiers <a id="fs.path.modifiers">[[fs.path.modifiers]]</a>
 ``` cpp
 void clear() noexcept;
 ```
+*Ensures:* `empty() == true`.
 ``` cpp
 path& make_preferred();
 ```
 ``` cpp
 path& remove_filename();
 ```
 *Effects:* Remove the generic format pathname of `filename()` from the
 generic format pathname.
+*Ensures:* `!has_filename()`.
 *Returns:* `*this`.
 [*Example 4*:
 ``` cpp
 path& replace_extension(const path& replacement = path());
 ```
 *Effects:*
+- Any existing `extension()` [[fs.path.decompose]] is removed from the
+  pathname in the generic format, then
 - If `replacement` is not empty and does not begin with a dot character,
   a dot character is appended to the pathname in the generic format,
   then
 - `operator+=(replacement);`.
 *Effects:* Swaps the contents (in all formats) of the two paths.
 *Complexity:* Constant time.
+##### Native format observers <a id="fs.path.native.obs">[[fs.path.native.obs]]</a>
 The string returned by all native format observers is in the native
+pathname format [[fs.class.path]].
 ``` cpp
 const string_type& native() const noexcept;
 ```
 ``` cpp
 const value_type* c_str() const noexcept;
 ```
+*Effects:* Equivalent to: `return native().c_str();`
 ``` cpp
 operator string_type() const;
 ```
 [[fs.path.cvt]].
 ``` cpp
 std::string string() const;
 std::wstring wstring() const;
+std::u8string u8string() const;
 std::u16string u16string() const;
 std::u32string u32string() const;
 ```
+*Returns:* `native()`.
 *Remarks:* Conversion, if any, is performed as specified by
+[[fs.path.cvt]].
+##### Generic format observers <a id="fs.path.generic.obs">[[fs.path.generic.obs]]</a>
 Generic format observer functions return strings formatted according to
+the generic pathname format [[fs.path.generic]]. A single slash (`'/'`)
+character is used as the *directory-separator*.
 [*Example 1*:
 On an operating system that uses backslash as its *preferred-separator*,
 [[fs.path.cvt]].
 ``` cpp
 std::string generic_string() const;
 std::wstring generic_wstring() const;
+std::u8string generic_u8string() const;
 std::u16string generic_u16string() const;
 std::u32string generic_u32string() const;
 ```
 *Returns:* The pathname in the generic format.
+*Remarks:* Conversion, if any, is specified by  [[fs.path.cvt]].
+##### Compare <a id="fs.path.compare">[[fs.path.compare]]</a>
 ``` cpp
 int compare(const path& p) const noexcept;
 ```
 *Returns:*
+- Let `rootNameComparison` be the result of
+  `this->root_name().native().compare(p.root_name().native())`. If
+ `rootNameComparison` is not `0`, `rootNameComparison`.
+- Otherwise, if `!this->has_root_directory()` and
+  `p.has_root_directory()`, a value less than `0`.
+- Otherwise, if `this->has_root_directory()` and
+  `!p.has_root_directory()`, a value greater than `0`.
+- Otherwise, if `native()` for the elements of `this->relative_path()`
+ are lexicographically less than `native()` for the elements of
+ `p.relative_path()`, a value less than `0`.
+- Otherwise, if `native()` for the elements of `this->relative_path()`
+  are lexicographically greater than `native()` for the elements of
+  `p.relative_path()`, a value greater than `0`.
+- Otherwise, `0`.
 ``` cpp
+int compare(const string_type& s) const;
 int compare(basic_string_view<value_type> s) const;
+int compare(const value_type* s) const;
 ```
+*Effects:* Equivalent to: `return compare(path(s));`
+##### Decomposition <a id="fs.path.decompose">[[fs.path.decompose]]</a>
 ``` cpp
 path root_name() const;
 ```
 ``` cpp
 path relative_path() const;
 ```
 *Returns:* A `path` composed from the pathname in the generic format, if
+`empty()` is `false`, beginning with the first *filename* after
+`root_path()`. Otherwise, `path()`.
 ``` cpp
 path parent_path() const;
 ```
+*Returns:* `*this` if `has_relative_path()` is `false`, otherwise a path
+whose generic format pathname is the longest prefix of the generic
+format pathname of `*this` that produces one fewer element in its
+iteration.
 ``` cpp
 path filename() const;
 ```
 ``` cpp
 path extension() const;
 ```
+*Returns:* A path whose pathname in the generic format is the suffix of
 `filename()` not included in `stem()`.
 [*Example 8*:
 ``` cpp
 [*Note 5*: On non-POSIX operating systems, for a path `p`, it may not
 be the case that `p.stem() + p.extension() == p.filename()`, even though
 the generic format pathnames are the same. — *end note*]
+##### Query <a id="fs.path.query">[[fs.path.query]]</a>
 ``` cpp
+[[nodiscard]] bool empty() const noexcept;
 ```
+*Returns:* `true` if the pathname in the generic format is empty,
+otherwise `false`.
 ``` cpp
 bool has_root_path() const;
 ```
 ``` cpp
 bool is_absolute() const;
 ```
 *Returns:* `true` if the pathname in the native format contains an
+absolute path [[fs.class.path]], otherwise `false`.
 [*Example 9*: `path("/").is_absolute()` is `true` for POSIX-based
 operating systems, and `false` for Windows-based operating
 systems. — *end example*]
 bool is_relative() const;
 ```
 *Returns:* `!is_absolute()`.
+##### Generation <a id="fs.path.gen">[[fs.path.gen]]</a>
 ``` cpp
 path lexically_normal() const;
 ```
 *Returns:* A path whose pathname in the generic format is the normal
+form [[fs.path.generic]] of the pathname in the generic format of
 `*this`.
 [*Example 10*:
 ``` cpp
 ``` cpp
 path lexically_relative(const path& base) const;
 ```
 *Returns:* `*this` made relative to `base`. Does not
+resolve [[fs.class.path]] symlinks. Does not first
+normalize [[fs.path.generic]] `*this` or `base`.
+*Effects:* If:
+- `root_name() != base.root_name()` is `true`, or
+- `is_absolute() != base.is_absolute()` is `true`, or
+- `!has_root_directory() && base.has_root_directory()` is `true`, or
+- any *filename* in `relative_path()` or `base.relative_path()` can be
+  interpreted as a *root-name*,
+returns `path()`.
+[*Note 6*: On a POSIX implementation, no *filename* in a
+*relative-path* is acceptable as a *root-name*. — *end note*]
+Determines the first mismatched element of `*this` and `base` as if by:
 ``` cpp
 auto [a, b] = mismatch(begin(), end(), base.begin(), base.end());
 ```
 Then,
 - if `a == end()` and `b == base.end()`, returns `path(".")`; otherwise
 - let `n` be the number of *filename* elements in \[`b`, `base.end()`)
+  that are not dot or dot-dot or empty, minus the number that are
+ dot-dot. If `n<0,` returns `path()`; otherwise
+- if `n == 0` and `(a == end() || a->empty())`, returns `path(".")`;
+  otherwise
 - returns an object of class `path` that is default-constructed,
   followed by
   - application of `operator/=(path(".."))` `n` times, and then
   - application of `operator/=` for each element in \[`a`, `end()`).
 *directory-separator* characters will be backslashes rather than
 slashes, but that does not affect `path` equality.
 — *end example*]
+[*Note 7*: If symlink following semantics are desired, use the
 operational function `relative()`. — *end note*]
+[*Note 8*: If normalization [[fs.path.generic]] is needed to ensure
+consistent matching of elements, apply `lexically_normal()` to `*this`,
+`base`, or both. — *end note*]
 ``` cpp
 path lexically_proximate(const path& base) const;
 ```
 *Returns:* If the value of `lexically_relative(base)` is not an empty
 path, return it. Otherwise return `*this`.
+[*Note 9*: If symlink following semantics are desired, use the
 operational function `proximate()`. — *end note*]
+[*Note 10*: If normalization [[fs.path.generic]] is needed to ensure
+consistent matching of elements, apply `lexically_normal()` to `*this`,
+`base`, or both. — *end note*]
+#### Iterators <a id="fs.path.itr">[[fs.path.itr]]</a>
 Path iterators iterate over the elements of the pathname in the generic
+format [[fs.path.generic]].
+A `path::iterator` is a constant iterator meeting all the requirements
+of a bidirectional iterator [[bidirectional.iterators]] except that, for
+dereferenceable iterators `a` and `b` of type `path::iterator` with
+`a == b`, there is no requirement that `*a` and `*b` are bound to the
+same object. Its `value_type` is `path`.
 Calling any non-const member function of a `path` object invalidates all
 iterators referring to elements of that object.
 For the elements of the pathname in the generic format, the forward
 iterator end() const;
 ```
 *Returns:* The end iterator.
+#### Inserter and extractor <a id="fs.path.io">[[fs.path.io]]</a>
+``` cpp
+template<class charT, class traits>
+  friend basic_ostream<charT, traits>&
+    operator<<(basic_ostream<charT, traits>& os, const path& p);
+```
+*Effects:* Equivalent to `os << quoted(p.string<charT, traits>())`.
+[*Note 1*: The `quoted` function is described
+in  [[quoted.manip]]. — *end note*]
+*Returns:* `os`.
+``` cpp
+template<class charT, class traits>
+  friend basic_istream<charT, traits>&
+    operator>>(basic_istream<charT, traits>& is, path& p);
+```
+*Effects:* Equivalent to:
+``` cpp
+basic_string<charT, traits> tmp;
+is >> quoted(tmp);
+p = tmp;
+```
+*Returns:* `is`.
+#### Non-member functions <a id="fs.path.nonmember">[[fs.path.nonmember]]</a>
 ``` cpp
 void swap(path& lhs, path& rhs) noexcept;
 ```
+*Effects:* Equivalent to `lhs.swap(rhs)`.
 ``` cpp
 size_t hash_value (const path& p) noexcept;
 ```
 *Returns:* A hash value for the path `p`. If for two paths, `p1 == p2`
 then `hash_value(p1) == hash_value(p2)`.
 ``` cpp
+friend bool operator==(const path& lhs, const path& rhs) noexcept;
 ```
+*Returns:* `lhs.compare(rhs) == 0`.
 [*Note 1*:
 Path equality and path equivalence have different semantics.
 - Equality is determined by the `path` non-member `operator==`, which
+  considers the two paths’ lexical representations only.
   \[*Example 1*: `path("foo") == "bar"` is never
   `true`. — *end example*]
 - Equivalence is determined by the `equivalent()` non-member function,
+  which determines if two paths resolve [[fs.class.path]] to the same
+  file system entity. \[*Example 2*: `equivalent("foo", "bar")` will be
+  `true` when both paths resolve to the same file. — *end example*]
 Programmers wishing to determine if two paths are “the same” must decide
 if “the same” means “the same representation” or “resolve to the same
 actual file”, and choose the appropriate function accordingly.
 — *end note*]
 ``` cpp
+friend strong_ordering operator<=>(const path& lhs, const path& rhs) noexcept;
 ```
+*Returns:* `lhs.compare(rhs) <=> 0`.
 ``` cpp
+friend path operator/ (const path& lhs, const path& rhs);
 ```
 *Effects:* Equivalent to: `return path(lhs) /= rhs;`
+### Class `filesystem_error` <a id="fs.class.filesystem.error">[[fs.class.filesystem.error]]</a>
 ``` cpp
 namespace std::filesystem {
   class filesystem_error : public system_error {
   public:
   };
 }
 ```
 The class `filesystem_error` defines the type of objects thrown as
+exceptions to report file system errors from functions described in
+subclause  [[filesystems]].
+#### Members <a id="fs.filesystem.error.members">[[fs.filesystem.error.members]]</a>
 Constructors are provided that store zero, one, or two paths associated
 with an error.
 ``` cpp
 filesystem_error(const string& what_arg, error_code ec);
 ```
+*Ensures:*
+- `code() == ec`,
+- `path1().empty() == true`,
+- `path2().empty() == true`, and
+- `string_view(what()).find(what_arg.c_str())` `!= string_view::npos`.
 ``` cpp
 filesystem_error(const string& what_arg, const path& p1, error_code ec);
 ```
+*Ensures:*
+- `code() == ec`,
+- `path1()` returns a reference to the stored copy of `p1`,
+- `path2().empty() == true`, and
+- `string_view(what()).find(what_arg.c_str())` `!= string_view::npos`.
 ``` cpp
 filesystem_error(const string& what_arg, const path& p1, const path& p2, error_code ec);
 ```
+*Ensures:*
+- `code() == ec`,
+- `path1()` returns a reference to the stored copy of `p1`,
+- `path2()` returns a reference to the stored copy of `p2`, and
+- `string_view(what()).find(what_arg.c_str())` `!= string_view::npos`.
 ``` cpp
 const path& path1() const noexcept;
 ```
 ``` cpp
 const char* what() const noexcept override;
 ```
+*Returns:* An NTBS that incorporates the `what_arg` argument supplied to
+the constructor. The exact format is unspecified. Implementations should
+include the `system_error::what()` string and the pathnames of `path1`
+and `path2` in the native format in the returned string.
 ### Enumerations <a id="fs.enum">[[fs.enum]]</a>
 #### Enum `path::format` <a id="fs.enum.path.format">[[fs.enum.path.format]]</a>
 This enum specifies constants used to identify the format of the
+character sequence, with the meanings listed in [[fs.enum.path.format]].
 [*Note 1*: For POSIX-based systems, native and generic formats are
 equivalent and the character sequence should always be interpreted in
 the same way. — *end note*]
+#### Enum class `file_type` <a id="fs.enum.file.type">[[fs.enum.file.type]]</a>
 This enum class specifies constants used to identify file types, with
+the meanings listed in [[fs.enum.file.type]]. The values of the
+constants are distinct.
 [*Note 1*: The file not being found is not considered an error while
 determining the type of a file. — *end note*]
 #### Enum class `copy_options` <a id="fs.enum.copy.opts">[[fs.enum.copy.opts]]</a>
+The `enum class` type `copy_options` is a bitmask type [[bitmask.types]]
+that specifies bitmask constants used to control the semantics of copy
+operations. The constants are specified in option groups with the
+meanings listed in [[fs.enum.copy.opts]]. The constant `none` represents
+the empty bitmask, and is shown in each option group for purposes of
 exposition; implementations shall provide only a single definition.
+Every other constant in the table represents a distinct bitmask element.
+**Table: Enum class `copy_options`** <a id="fs.enum.copy.opts">[fs.enum.copy.opts]</a>
 | Constant             | Meaning                                                                                                                                               |
 | -------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `none`               | (Default) Error; file already exists.                                                                                                                 |
 | `skip_existing`      | Do not overwrite existing file, do not report an error.                                                                                               |
 | `create_hard_links`  | Make hard links instead of copies of files.                                                                                                           |
 #### Enum class `perms` <a id="fs.enum.perms">[[fs.enum.perms]]</a>
+The `enum class` type `perms` is a bitmask type [[bitmask.types]] that
+specifies bitmask constants used to identify file permissions, with the
+meanings listed in [[fs.enum.perms]].
+**Table: Enum class `perms`** <a id="fs.enum.perms">[fs.enum.perms]</a>
 | Name           | Value (octal) | POSIX macro | Definition or notes                                                                                              |
 | -------------- | ------------- | ----------- | ---------------------------------------------------------------------------------------------------------------- |
 | `none`         | `0`           |             | There are no permissions set for the file.                                                                       |
 | `owner_read`   | `0400`        | `S_IRUSR`   | Read permission, owner                                                                                           |
 | `unknown`      | `0xFFFF`      |             | The permissions are not known, such as when a `file_status` object is created without specifying the permissions |
 #### Enum class `perm_options` <a id="fs.enum.perm.opts">[[fs.enum.perm.opts]]</a>
+The `enum class` type `perm_options` is a bitmask type [[bitmask.types]]
+that specifies bitmask constants used to control the semantics of
+permissions operations, with the meanings listed in
+[[fs.enum.perm.opts]]. The bitmask constants are bitmask elements. In
+[[fs.enum.perm.opts]] `perm` denotes a value of type `perms` passed to
+`permissions`.
+**Table: Enum class `perm_options`** <a id="fs.enum.perm.opts">[fs.enum.perm.opts]</a>
 | Name       | Meaning                                                                                                                                                 |
+| ---------- | ------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `replace`  | `permissions` shall replace the file's permission bits with `perm`                                                                                      |
+| `add`      | `permissions` shall replace the file's permission bits with the bitwise \logop{OR} of `perm` and the file's current permission bits.                    |
+| `remove`   | `permissions` shall replace the file's permission bits with the bitwise \logop{AND} of the complement of `perm` and the file's current permission bits. |
 | `nofollow` | `permissions` shall change the permissions of a symbolic link itself rather than the permissions of the file the link resolves to.                      |
 #### Enum class `directory_options` <a id="fs.enum.dir.opts">[[fs.enum.dir.opts]]</a>
+The `enum class` type `directory_options` is a bitmask type
+[[bitmask.types]] that specifies bitmask constants used to identify
+directory traversal options, with the meanings listed in
+[[fs.enum.dir.opts]]. The constant `none` represents the empty bitmask;
+every other constant in the table represents a distinct bitmask element.
+**Table: Enum class `directory_options`** <a id="fs.enum.dir.opts">[fs.enum.dir.opts]</a>
 | Name                       | Meaning                                                            |
 | -------------------------- | ------------------------------------------------------------------ |
 | `none`                     | (Default) Skip directory symlinks, permission denied is an error.  |
 | `follow_directory_symlink` | Follow rather than skip directory symlinks.                        |
 | `skip_permission_denied`   | Skip directories that would otherwise result in permission denied. |
+### Class `file_status` <a id="fs.class.file.status">[[fs.class.file.status]]</a>
 ``` cpp
 namespace std::filesystem {
   class file_status {
   public:
+    // [fs.file.status.cons], constructors and destructor
     file_status() noexcept : file_status(file_type::none) {}
     explicit file_status(file_type ft,
                          perms prms = perms::unknown) noexcept;
     file_status(const file_status&) noexcept = default;
     file_status(file_status&&) noexcept = default;
     ~file_status();
+    // assignments
     file_status& operator=(const file_status&) noexcept = default;
     file_status& operator=(file_status&&) noexcept = default;
+    // [fs.file.status.mods], modifiers
     void       type(file_type ft) noexcept;
     void       permissions(perms prms) noexcept;
+    // [fs.file.status.obs], observers
     file_type  type() const noexcept;
     perms      permissions() const noexcept;
+    friend bool operator==(const file_status& lhs, const file_status& rhs) noexcept
+      { return lhs.type() == rhs.type() && lhs.permissions() == rhs.permissions(); }
   };
 }
 ```
+#### Constructors <a id="fs.file.status.cons">[[fs.file.status.cons]]</a>
 ``` cpp
 explicit file_status(file_type ft, perms prms = perms::unknown) noexcept;
 ```
+*Ensures:* `type() == ft` and `permissions() == prms`.
+#### Observers <a id="fs.file.status.obs">[[fs.file.status.obs]]</a>
 ``` cpp
 file_type type() const noexcept;
 ```
 *Returns:* The value of `permissions()` specified by the postconditions
 of the most recent call to a constructor, `operator=`, or
 `permissions(perms)` function.
+#### Modifiers <a id="fs.file.status.mods">[[fs.file.status.mods]]</a>
 ``` cpp
 void type(file_type ft) noexcept;
 ```
+*Ensures:* `type() == ft`.
 ``` cpp
 void permissions(perms prms) noexcept;
 ```
+*Ensures:* `permissions() == prms`.
+### Class `directory_entry` <a id="fs.class.directory.entry">[[fs.class.directory.entry]]</a>
 ``` cpp
 namespace std::filesystem {
   class directory_entry {
   public:
     // [fs.dir.entry.cons], constructors and destructor
     directory_entry() noexcept = default;
     directory_entry(const directory_entry&) = default;
     directory_entry(directory_entry&&) noexcept = default;
+    explicit directory_entry(const filesystem::path& p);
+    directory_entry(const filesystem::path& p, error_code& ec);
     ~directory_entry();
+    // assignments
     directory_entry& operator=(const directory_entry&) = default;
     directory_entry& operator=(directory_entry&&) noexcept = default;
     // [fs.dir.entry.mods], modifiers
+    void assign(const filesystem::path& p);
+    void assign(const filesystem::path& p, error_code& ec);
+    void replace_filename(const filesystem::path& p);
+    void replace_filename(const filesystem::path& p, error_code& ec);
     void refresh();
     void refresh(error_code& ec) noexcept;
     // [fs.dir.entry.obs], observers
+    const filesystem::path& path() const noexcept;
+    operator const filesystem::path&() const noexcept;
     bool exists() const;
     bool exists(error_code& ec) const noexcept;
     bool is_block_file() const;
     bool is_block_file(error_code& ec) const noexcept;
     bool is_character_file() const;
     file_status status() const;
     file_status status(error_code& ec) const noexcept;
     file_status symlink_status() const;
     file_status symlink_status(error_code& ec) const noexcept;
     bool operator==(const directory_entry& rhs) const noexcept;
+ strong_ordering operator<=>(const directory_entry& rhs) const noexcept;
   private:
+ filesystem::path pathobject; // exposition only
     friend class directory_iterator;    // exposition only
   };
 }
 ```
 A `directory_entry` object stores a `path` object and may store
 additional objects for file attributes such as hard link count, status,
 symlink status, file size, and last write time.
+Implementations should store such additional file attributes during
+directory iteration if their values are available and storing the values
+would allow the implementation to eliminate file system accesses by
+`directory_entry` observer functions [[fs.op.funcs]]. Such stored file
+attribute values are said to be *cached*.
+[*Note 1*: For purposes of exposition, class `directory_iterator`
+[[fs.class.directory.iterator]] is shown above as a friend of class
 `directory_entry`. Friendship allows the `directory_iterator`
 implementation to cache already available attribute values directly into
 a `directory_entry` object without the cost of an unneeded call to
 `refresh()`. — *end note*]
 `std::filesystem::last_write_time` function. The code is portable to any
 implementation, regardless of whether or not it employs caching.
 — *end example*]
+#### Constructors <a id="fs.dir.entry.cons">[[fs.dir.entry.cons]]</a>
 ``` cpp
+explicit directory_entry(const filesystem::path& p);
+directory_entry(const filesystem::path& p, error_code& ec);
 ```
+*Effects:* Calls `refresh()` or `refresh(ec)`, respectively.
+*Ensures:* `path() == p` if no error occurs, otherwise
+`path() == filesystem::path()`.
 *Throws:* As specified in  [[fs.err.report]].
+#### Modifiers <a id="fs.dir.entry.mods">[[fs.dir.entry.mods]]</a>
 ``` cpp
+void assign(const filesystem::path& p);
+void assign(const filesystem::path& p, error_code& ec);
 ```
 *Effects:* Equivalent to `pathobject = p`, then `refresh()` or
 `refresh(ec)`, respectively. If an error occurs, the values of any
 cached attributes are unspecified.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
+void replace_filename(const filesystem::path& p);
+void replace_filename(const filesystem::path& p, error_code& ec);
 ```
 *Effects:* Equivalent to `pathobject.replace_filename(p)`, then
 `refresh()` or `refresh(ec)`, respectively. If an error occurs, the
 values of any cached attributes are unspecified.
 void refresh(error_code& ec) noexcept;
 ```
 *Effects:* Stores the current values of any cached attributes of the
 file `p` resolves to. If an error occurs, an error is
+reported [[fs.err.report]] and the values of any cached attributes are
+unspecified.
 *Throws:* As specified in  [[fs.err.report]].
+[*Note 1*: Implementations of `directory_iterator`
+[[fs.class.directory.iterator]] are prohibited from directly or
+indirectly calling the `refresh` function since it must access the
+external file system, and the objective of caching is to avoid
+unnecessary file system accesses. — *end note*]
+#### Observers <a id="fs.dir.entry.obs">[[fs.dir.entry.obs]]</a>
 Unqualified function names in the *Returns:* elements of the
 `directory_entry` observers described below refer to members of the
 `std::filesystem` namespace.
 ``` cpp
+const filesystem::path& path() const noexcept;
+operator const filesystem::path&() const noexcept;
 ```
 *Returns:* `pathobject`.
 ``` cpp
 bool exists() const;
 bool exists(error_code& ec) const noexcept;
 ```
+*Returns:* `exists(this->status())` or `exists(this->status(ec))`,
 respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_block_file() const;
 bool is_block_file(error_code& ec) const noexcept;
 ```
 *Returns:* `is_block_file(this->status())` or
+`is_block_file(this->status(ec))`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_character_file() const;
 bool is_character_file(error_code& ec) const noexcept;
 ```
 *Returns:* `is_character_file(this->status())` or
+`is_character_file(this->status(ec))`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_directory() const;
 bool is_directory(error_code& ec) const noexcept;
 ```
 *Returns:* `is_directory(this->status())` or
+`is_directory(this->status(ec))`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_fifo() const;
 bool is_fifo(error_code& ec) const noexcept;
 ```
+*Returns:* `is_fifo(this->status())` or `is_fifo(this->status(ec))`,
 respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_other() const;
 bool is_other(error_code& ec) const noexcept;
 ```
+*Returns:* `is_other(this->status())` or `is_other(this->status(ec))`,
 respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_regular_file() const;
 bool is_regular_file(error_code& ec) const noexcept;
 ```
 *Returns:* `is_regular_file(this->status())` or
+`is_regular_file(this->status(ec))`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_socket() const;
 bool is_socket(error_code& ec) const noexcept;
 ```
+*Returns:* `is_socket(this->status())` or `is_socket(this->status(ec))`,
+respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool is_symlink() const;
 bool is_symlink(error_code& ec) const noexcept;
 ```
 *Returns:* `is_symlink(this->symlink_status())` or
+`is_symlink(this->symlink_status(ec))`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 uintmax_t file_size() const;
 ```
 *Returns:* `pathobject == rhs.pathobject`.
 ``` cpp
+strong_ordering operator<=>(const directory_entry& rhs) const noexcept;
 ```
+*Returns:* `pathobject <=> rhs.pathobject`.
+### Class `directory_iterator` <a id="fs.class.directory.iterator">[[fs.class.directory.iterator]]</a>
 An object of type `directory_iterator` provides an iterator for a
 sequence of `directory_entry` elements representing the path and any
+cached attribute values [[fs.class.directory.entry]] for each file in a
+directory or in an *implementation-defined* directory-like file type.
 [*Note 1*: For iteration into sub-directories, see class
+`recursive_directory_iterator` [[fs.class.rec.dir.itr]]. — *end note*]
 ``` cpp
 namespace std::filesystem {
   class directory_iterator {
   public:
     // [fs.dir.itr.members], member functions
     directory_iterator() noexcept;
     explicit directory_iterator(const path& p);
     directory_iterator(const path& p, directory_options options);
+    directory_iterator(const path& p, error_code& ec);
     directory_iterator(const path& p, directory_options options,
+                       error_code& ec);
     directory_iterator(const directory_iterator& rhs);
     directory_iterator(directory_iterator&& rhs) noexcept;
     ~directory_iterator();
     directory_iterator& operator=(const directory_iterator& rhs);
     directory_iterator& operator=(directory_iterator&& rhs) noexcept;
     const directory_entry& operator*() const;
     const directory_entry* operator->() const;
     directory_iterator&    operator++();
+    directory_iterator&    increment(error_code& ec);
     // other members as required by [input.iterators], input iterators
   };
 }
 ```
+`directory_iterator` meets the *Cpp17InputIterator* requirements
+[[input.iterators]].
 If an iterator of type `directory_iterator` reports an error or is
 advanced past the last directory element, that iterator shall become
 equal to the end iterator value. The `directory_iterator` default
 constructor shall create an iterator equal to the end iterator value,
 to a `path` object composed of the directory argument from which the
 iterator was constructed with filename of the directory entry appended
 as if by `operator/=`.
 Directory iteration shall not yield directory entries for the current
+(dot) and parent (dot-dot) directories.
 The order of directory entries obtained by dereferencing successive
 increments of a `directory_iterator` is unspecified.
 Constructors and non-const `directory_iterator` member functions store
+the values of any cached attributes [[fs.class.directory.entry]] in the
+`directory_entry` element returned by `operator*()`.
 `directory_iterator` member functions shall not directly or indirectly
 call any `directory_entry` `refresh` function.
 [*Note 2*: The exact mechanism for storing cached attribute values is
 not exposed to users. For exposition, class `directory_iterator` is
+shown in [[fs.class.directory.entry]] as a friend of class
 `directory_entry`. — *end note*]
 [*Note 3*: Programs performing directory iteration may wish to test if
 the path obtained by dereferencing a directory iterator actually exists.
 It could be a symbolic link to a non-existent file. Programs recursively
 construction of a `directory_iterator` for the directory, it is
 unspecified whether or not subsequently incrementing the iterator will
 ever result in an iterator referencing the removed or added directory
 entry. See POSIX `readdir_r`. — *end note*]
+#### Members <a id="fs.dir.itr.members">[[fs.dir.itr.members]]</a>
 ``` cpp
 directory_iterator() noexcept;
 ```
 *Effects:* Constructs the end iterator.
 ``` cpp
 explicit directory_iterator(const path& p);
 directory_iterator(const path& p, directory_options options);
+directory_iterator(const path& p, error_code& ec);
+directory_iterator(const path& p, directory_options options, error_code& ec);
 ```
 *Effects:* For the directory that `p` resolves to, constructs an
 iterator for the first element in a sequence of `directory_entry`
 elements representing the files in the directory, if any; otherwise the
 ``` cpp
 directory_iterator(const directory_iterator& rhs);
 directory_iterator(directory_iterator&& rhs) noexcept;
 ```
+*Ensures:* `*this` has the original value of `rhs`.
 ``` cpp
 directory_iterator& operator=(const directory_iterator& rhs);
 directory_iterator& operator=(directory_iterator&& rhs) noexcept;
 ```
 *Effects:* If `*this` and `rhs` are the same object, the member has no
 effect.
+*Ensures:* `*this` has the original value of `rhs`.
 *Returns:* `*this`.
 ``` cpp
 directory_iterator& operator++();
+directory_iterator& increment(error_code& ec);
 ```
 *Effects:* As specified for the prefix increment operation of Input
+iterators [[input.iterators]].
 *Returns:* `*this`.
 *Throws:* As specified in  [[fs.err.report]].
+#### Non-member functions <a id="fs.dir.itr.nonmembers">[[fs.dir.itr.nonmembers]]</a>
 These functions enable range access for `directory_iterator`.
 ``` cpp
 directory_iterator begin(directory_iterator iter) noexcept;
     // [fs.rec.dir.itr.members], constructors and destructor
     recursive_directory_iterator() noexcept;
     explicit recursive_directory_iterator(const path& p);
     recursive_directory_iterator(const path& p, directory_options options);
     recursive_directory_iterator(const path& p, directory_options options,
+                                 error_code& ec);
+    recursive_directory_iterator(const path& p, error_code& ec);
     recursive_directory_iterator(const recursive_directory_iterator& rhs);
     recursive_directory_iterator(recursive_directory_iterator&& rhs) noexcept;
     ~recursive_directory_iterator();
     // [fs.rec.dir.itr.members], observers
       operator=(const recursive_directory_iterator& rhs);
     recursive_directory_iterator&
       operator=(recursive_directory_iterator&& rhs) noexcept;
     recursive_directory_iterator& operator++();
+    recursive_directory_iterator& increment(error_code& ec);
     void pop();
     void pop(error_code& ec);
     void disable_recursion_pending();
 `directory_iterator` unless otherwise specified.
 [*Note 1*: If the directory structure being iterated over contains
 cycles then the end iterator may be unreachable. — *end note*]
+#### Members <a id="fs.rec.dir.itr.members">[[fs.rec.dir.itr.members]]</a>
 ``` cpp
 recursive_directory_iterator() noexcept;
 ```
 *Effects:* Constructs the end iterator.
 ``` cpp
 explicit recursive_directory_iterator(const path& p);
 recursive_directory_iterator(const path& p, directory_options options);
+recursive_directory_iterator(const path& p, directory_options options, error_code& ec);
+recursive_directory_iterator(const path& p, error_code& ec);
 ```
+*Effects:* Constructs an iterator representing the first entry in the
+directory to which `p` resolves, if any; otherwise, the end iterator.
+However, if
 ``` cpp
 (options & directory_options::skip_permission_denied) != directory_options::none
 ```
 and construction encounters an error indicating that permission to
 access `p` is denied, constructs the end iterator and does not report an
 error.
+*Ensures:* `options() == options` for the signatures with a
 `directory_options` argument, otherwise
 `options() == directory_options::none`.
 *Throws:* As specified in  [[fs.err.report]].
 `recursive_directory_iterator(".")` rather than
 `recursive_directory_iterator("")`. — *end note*]
 [*Note 2*: By default, `recursive_directory_iterator` does not follow
 directory symlinks. To follow directory symlinks, specify `options` as
+`directory_options::follow_directory_symlink`. — *end note*]
 ``` cpp
 recursive_directory_iterator(const recursive_directory_iterator& rhs);
 ```
+*Ensures:*
 - `options() == rhs.options()`
 - `depth() == rhs.depth()`
 - `recursion_pending() == rhs.recursion_pending()`
 ``` cpp
 recursive_directory_iterator(recursive_directory_iterator&& rhs) noexcept;
 ```
+*Ensures:* `options()`, `depth()`, and `recursion_pending()` have the
+values that `rhs.options()`, `rhs.depth()`, and
 `rhs.recursion_pending()`, respectively, had before the function call.
 ``` cpp
 recursive_directory_iterator& operator=(const recursive_directory_iterator& rhs);
 ```
 *Effects:* If `*this` and `rhs` are the same object, the member has no
 effect.
+*Ensures:*
 - `options() == rhs.options()`
 - `depth() == rhs.depth()`
 - `recursion_pending() == rhs.recursion_pending()`
 ```
 *Effects:* If `*this` and `rhs` are the same object, the member has no
 effect.
+*Ensures:* `options()`, `depth()`, and `recursion_pending()` have the
+values that `rhs.options()`, `rhs.depth()`, and
 `rhs.recursion_pending()`, respectively, had before the function call.
 *Returns:* `*this`.
 ``` cpp
 *Throws:* Nothing.
 ``` cpp
 recursive_directory_iterator& operator++();
+recursive_directory_iterator& increment(error_code& ec);
 ```
 *Effects:* As specified for the prefix increment operation of Input
+iterators [[input.iterators]], except that:
 - If there are no more entries at the current depth, then if
   `depth() != 0` iteration over the parent directory resumes; otherwise
   `*this = recursive_directory_iterator()`.
 - Otherwise if
 directory currently being iterated over, and continue iteration over the
 parent directory.
 *Throws:* As specified in  [[fs.err.report]].
+*Remarks:* Any copies of the previous value of `*this` are no longer
+required to be dereferenceable nor to be in the domain of `==`.
 ``` cpp
 void disable_recursion_pending();
 ```
+*Ensures:* `recursion_pending() == false`.
 [*Note 4*: `disable_recursion_pending``()` is used to prevent unwanted
 recursion into a directory. — *end note*]
+#### Non-member functions <a id="fs.rec.dir.itr.nonmembers">[[fs.rec.dir.itr.nonmembers]]</a>
 These functions enable use of `recursive_directory_iterator` with
 range-based for statements.
 ``` cpp
 Filesystem operation functions query or modify files, including
 directories, in external storage.
 [*Note 1*: Because hardware failures, network failures, file system
+races [[fs.race.behavior]], and many other kinds of errors occur
 frequently in file system operations, users should be aware that any
 filesystem operation function, no matter how apparently innocuous, may
 encounter an error; see  [[fs.err.report]]. — *end note*]
 #### Absolute <a id="fs.op.absolute">[[fs.op.absolute]]</a>
 path absolute(const path& p);
 path absolute(const path& p, error_code& ec);
 ```
 *Effects:* Composes an absolute path referencing the same file system
+location as `p` according to the operating system [[fs.conform.os]].
 *Returns:* The composed path. The signature with argument `ec` returns
 `path()` if an error occurs.
 [*Note 1*: For the returned path, `rp`, `rp.is_absolute()` is `true`
 *Throws:* As specified in  [[fs.err.report]].
 [*Note 2*: To resolve symlinks, or perform other sanitization which
 might require queries to secondary storage, such as hard disks, consider
+`canonical` [[fs.op.canonical]]. — *end note*]
 [*Note 3*: Implementations are strongly encouraged to not query
 secondary storage, and not consider `!exists(p)` an
 error. — *end note*]
 `GetFullPathNameW`. — *end example*]
 #### Canonical <a id="fs.op.canonical">[[fs.op.canonical]]</a>
 ``` cpp
+path canonical(const path& p);
 path canonical(const path& p, error_code& ec);
 ```
+*Effects:* Converts `p` to an absolute path that has no symbolic link,
+dot, or dot-dot elements in its pathname in the generic format.
 *Returns:* A path that refers to the same file system object as
+`absolute(p)`. The signature with argument `ec` returns `path()` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 *Remarks:* `!exists(p)` is an error.
 ```
 *Effects:* Equivalent to `copy(from, to, copy_options::none)`.
 ``` cpp
+void copy(const path& from, const path& to, error_code& ec);
 ```
 *Effects:* Equivalent to `copy(from, to, copy_options::none, ec)`.
 ``` cpp
 void copy(const path& from, const path& to, copy_options options);
 void copy(const path& from, const path& to, copy_options options,
+          error_code& ec);
 ```
+*Preconditions:* At most one element from each option
+group [[fs.enum.copy.opts]] is set in `options`.
 *Effects:* Before the first use of `f` and `t`:
 - If
   ``` cpp
   `auto t = status(to)`.
 Effects are then as follows:
 - If `f.type()` or `t.type()` is an implementation-defined file
+  type [[fs.enum.file.type]], then the effects are
   *implementation-defined*.
 - Otherwise, an error is reported as specified in  [[fs.err.report]] if:
+  - `exists(f)` is `false`, or
+  - `equivalent(from, to)` is `true`, or
+  - `is_other(f) || is_other(t)` is `true`, or
+  - `is_directory(f) && is_regular_file(t)` is `true`.
 - Otherwise, if `is_symlink(f)`, then:
   - If `(options & copy_options::skip_symlinks) != copy_options::none`
     then return.
   - Otherwise if
     ``` cpp
     `(options & copy_options::create_hard_links) != copy_options::none`,
     then create a hard link to the source file.
   - Otherwise, if `is_directory(t)`, then
     `copy_file(from, to/from.filename(), options)`.
   - Otherwise, `copy_file(from, to, options)`.
+- Otherwise, if
+  ``` cpp
+  is_directory(f) &&
+  (options & copy_options::create_symlinks) != copy_options::none
+  ```
+  then report an error with an `error_code` argument equal to
+  `make_error_code(errc::is_a_directory)`.
 - Otherwise, if
   ``` cpp
   is_directory(f) &&
   ((options & copy_options::recursive) != copy_options::none ||
    options == copy_options::none)
   ```
   then:
+  - If `exists(t)` is `false`, then `create_directory(to, from)`.
   - Then, iterate over the files in `from`, as if by
     ``` cpp
     for (const directory_entry& x : directory_iterator(from))
+      copy(x.path(), to/x.path().filename(),
+           options | copy_options::in-recursive-copy);
     ```
+    where *`in-recursive-copy`* is a bitmask element of `copy_options`
+    that is not one of the elements in  [[fs.enum.copy.opts]].
 - Otherwise, for the signature with argument `ec`, `ec.clear()`.
 - Otherwise, no effects.
 *Throws:* As specified in  [[fs.err.report]].
     file3
 ```
 — *end example*]
+#### Copy file <a id="fs.op.copy.file">[[fs.op.copy.file]]</a>
 ``` cpp
 bool copy_file(const path& from, const path& to);
+bool copy_file(const path& from, const path& to, error_code& ec);
 ```
 *Returns:* `copy_file(from, to, copy_options::none)` or
 `copy_file(from, to, copy_options::none, ec)`, respectively.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool copy_file(const path& from, const path& to, copy_options options);
 bool copy_file(const path& from, const path& to, copy_options options,
+               error_code& ec);
 ```
+*Preconditions:* At most one element from each option
+group [[fs.enum.copy.opts]] is set in `options`.
 *Effects:* As follows:
+- Report an error as specified in  [[fs.err.report]] if:
+ - `is_regular_file(from)` is `false`, or
+  - `exists(to)` is `true` and `is_regular_file(to)` is `false`, or
+  - `exists(to)` is `true` and `equivalent(from, to)` is `true`, or
+  - `exists(to)` is `true` and
     ``` cpp
     (options & (copy_options::skip_existing |
                 copy_options::overwrite_existing |
                 copy_options::update_existing)) == copy_options::none
     ```
 - Otherwise, copy the contents and attributes of the file `from`
   resolves to, to the file `to` resolves to, if:
+  - `exists(to)` is `false`, or
   - `(options & copy_options::overwrite_existing) != copy_options::none`,
     or
   - `(options & copy_options::update_existing) `` `` != copy_options::none`
     and `from` is more recent than `to`, determined as if by use of the
+    `last_write_time` function [[fs.op.last.write.time]].
 - Otherwise, no effects.
 *Returns:* `true` if the `from` file was copied, otherwise `false`. The
 signature with argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 *Complexity:* At most one direct or indirect invocation of `status(to)`.
+#### Copy symlink <a id="fs.op.copy.symlink">[[fs.op.copy.symlink]]</a>
 ``` cpp
 void copy_symlink(const path& existing_symlink, const path& new_symlink);
 void copy_symlink(const path& existing_symlink, const path& new_symlink,
                   error_code& ec) noexcept;
 respectively, where in each case *`function`* is `create_symlink` or
 `create_directory_symlink` as appropriate.
 *Throws:* As specified in  [[fs.err.report]].
+#### Create directories <a id="fs.op.create.directories">[[fs.op.create.directories]]</a>
 ``` cpp
 bool create_directories(const path& p);
+bool create_directories(const path& p, error_code& ec);
 ```
+*Effects:* Calls `create_directory()` for each element of `p` that does
 not exist.
+*Returns:* `true` if a new directory was created for the directory `p`
+resolves to, otherwise `false`.
+*Throws:* As specified in  [[fs.err.report]].
+*Complexity:* 𝑂(n) where *n* is the number of elements of `p`.
+#### Create directory <a id="fs.op.create.directory">[[fs.op.create.directory]]</a>
 ``` cpp
 bool create_directory(const path& p);
 bool create_directory(const path& p, error_code& ec) noexcept;
 ```
+*Effects:* Creates the directory `p` resolves to, as if by POSIX `mkdir`
+with a second argument of `static_cast<int>(perms::all)`. If `mkdir`
+fails because `p` resolves to an existing directory, no error is
+reported. Otherwise on failure an error is reported.
+*Returns:* `true` if a new directory was created, otherwise `false`.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 bool create_directory(const path& p, const path& existing_p);
 bool create_directory(const path& p, const path& existing_p, error_code& ec) noexcept;
 ```
+*Effects:* Creates the directory `p` resolves to, with attributes copied
+from directory `existing_p`. The set of attributes copied is operating
+system dependent. If `mkdir` fails because `p` resolves to an existing
+directory, no error is reported. Otherwise on failure an error is
+reported.
 [*Note 1*: For POSIX-based operating systems, the attributes are those
 copied by native API `stat(existing_p.c_str(), &attributes_stat)`
 followed by `mkdir(p.c_str(), attributes_stat.st_mode)`. For
 Windows-based operating systems, the attributes are those copied by
 native API
 `CreateDirectoryExW(existing_p.c_str(), p.c_str(), 0)`. — *end note*]
+*Returns:* `true` if a new directory was created with attributes copied
+from directory `existing_p`, otherwise `false`.
 *Throws:* As specified in  [[fs.err.report]].
+#### Create directory symlink <a id="fs.op.create.dir.symlk">[[fs.op.create.dir.symlk]]</a>
 ``` cpp
 void create_directory_symlink(const path& to, const path& new_symlink);
 void create_directory_symlink(const path& to, const path& new_symlink,
                               error_code& ec) noexcept;
 ```
 *Effects:* Establishes the postcondition, as if by POSIX `symlink()`.
+*Ensures:* `new_symlink` resolves to a symbolic link file that contains
+an unspecified representation of `to`.
 *Throws:* As specified in  [[fs.err.report]].
 [*Note 1*: Some operating systems require symlink creation to identify
 that the link is to a directory. Portable code should use
 [*Note 2*: Some operating systems do not support symbolic links at all
 or support them only for regular files. Some file systems (such as the
 FAT file system) do not support symbolic links regardless of the
 operating system. — *end note*]
+#### Create hard link <a id="fs.op.create.hard.lk">[[fs.op.create.hard.lk]]</a>
 ``` cpp
 void create_hard_link(const path& to, const path& new_hard_link);
 void create_hard_link(const path& to, const path& new_hard_link,
                                       error_code& ec) noexcept;
 ```
 *Effects:* Establishes the postcondition, as if by POSIX `link()`.
+*Ensures:*
 - `exists(to) && exists(new_hard_link) && equivalent(to, new_hard_link)`
 - The contents of the file or directory `to` resolves to are unchanged.
 *Throws:* As specified in  [[fs.err.report]].
 support them only for regular files. Some file systems (such as the FAT
 file system) do not support hard links regardless of the operating
 system. Some file systems limit the number of links per
 file. — *end note*]
+#### Create symlink <a id="fs.op.create.symlink">[[fs.op.create.symlink]]</a>
 ``` cpp
 void create_symlink(const path& to, const path& new_symlink);
 void create_symlink(const path& to, const path& new_symlink,
                     error_code& ec) noexcept;
 ```
 *Effects:* Establishes the postcondition, as if by POSIX `symlink()`.
+*Ensures:* `new_symlink` resolves to a symbolic link file that contains
+an unspecified representation of `to`.
 *Throws:* As specified in  [[fs.err.report]].
 [*Note 1*: Some operating systems do not support symbolic links at all
 or support them only for regular files. Some file systems (such as the
 FAT file system) do not support symbolic links regardless of the
 operating system. — *end note*]
+#### Current path <a id="fs.op.current.path">[[fs.op.current.path]]</a>
 ``` cpp
 path current_path();
 path current_path(error_code& ec);
 ```
 [*Note 1*: The `current_path()` name was chosen to emphasize that the
 returned value is a path, not just a single directory
 name. — *end note*]
 [*Note 2*: The current path as returned by many operating systems is a
+dangerous global variable. It may be changed unexpectedly by third-party
+or system library functions, or by another thread. — *end note*]
 ``` cpp
 void current_path(const path& p);
 void current_path(const path& p, error_code& ec) noexcept;
 ```
 *Effects:* Establishes the postcondition, as if by POSIX `chdir()`.
+*Ensures:* `equivalent(p, current_path())`.
 *Throws:* As specified in  [[fs.err.report]].
 [*Note 3*: The current path for many operating systems is a dangerous
 global state. It may be changed unexpectedly by a third-party or system
 ``` cpp
 bool equivalent(const path& p1, const path& p2);
 bool equivalent(const path& p1, const path& p2, error_code& ec) noexcept;
 ```
+*Returns:* `true`, if `p1` and `p2` resolve to the same file system
+entity, otherwise `false`. The signature with argument `ec` returns
+`false` if an error occurs.
 Two paths are considered to resolve to the same file system entity if
 two candidate entities reside on the same device at the same location.
+[*Note 1*: On POSIX platforms, this is determined as if by the values
+of the POSIX `stat` class, obtained as if by `stat()` for the two paths,
+having equal `st_dev` values and equal `st_ino` values. — *end note*]
+*Remarks:* `!exists(p1) || !exists(p2)` is an error.
 *Throws:* As specified in  [[fs.err.report]].
 #### Exists <a id="fs.op.exists">[[fs.op.exists]]</a>
 *Returns:* `exists(s)`.
 *Throws:* As specified in  [[fs.err.report]].
+#### File size <a id="fs.op.file.size">[[fs.op.file.size]]</a>
 ``` cpp
 uintmax_t file_size(const path& p);
 uintmax_t file_size(const path& p, error_code& ec) noexcept;
 ```
+*Effects:* If `exists(p)` is `false`, an error is
+reported [[fs.err.report]].
 *Returns:*
+- If `is_regular_file(p)`, the size in bytes of the file `p` resolves
+  to, determined as if by the value of the POSIX `stat` class member
+ `st_size` obtained as if by POSIX `stat()`.
 - Otherwise, the result is *implementation-defined*.
 The signature with argument `ec` returns `static_cast<uintmax_t>(-1)` if
 an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Hard link count <a id="fs.op.hard.lk.ct">[[fs.op.hard.lk.ct]]</a>
 ``` cpp
 uintmax_t hard_link_count(const path& p);
 uintmax_t hard_link_count(const path& p, error_code& ec) noexcept;
 ```
 *Returns:* The number of hard links for `p`. The signature with argument
 `ec` returns `static_cast<uintmax_t>(-1)` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Is block file <a id="fs.op.is.block.file">[[fs.op.is.block.file]]</a>
 ``` cpp
 bool is_block_file(file_status s) noexcept;
 ```
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Is character file <a id="fs.op.is.char.file">[[fs.op.is.char.file]]</a>
 ``` cpp
 bool is_character_file(file_status s) noexcept;
 ```
 `is_character_file(status(p, ec))`, respectively.
 The signature with argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Is directory <a id="fs.op.is.directory">[[fs.op.is.directory]]</a>
 ``` cpp
 bool is_directory(file_status s) noexcept;
 ```
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Is empty <a id="fs.op.is.empty">[[fs.op.is.empty]]</a>
 ``` cpp
 bool is_empty(const path& p);
+bool is_empty(const path& p, error_code& ec);
 ```
 *Effects:*
 - Determine `file_status s`, as if by `status(p)` or `status(p, ec)`,
     occurred.
   - Otherwise, return `sz == 0`.
 *Throws:* As specified in  [[fs.err.report]].
+#### Is fifo <a id="fs.op.is.fifo">[[fs.op.is.fifo]]</a>
 ``` cpp
 bool is_fifo(file_status s) noexcept;
 ```
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Is other <a id="fs.op.is.other">[[fs.op.is.other]]</a>
 ``` cpp
 bool is_other(file_status s) noexcept;
 ```
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Is regular file <a id="fs.op.is.regular.file">[[fs.op.is.regular.file]]</a>
 ``` cpp
 bool is_regular_file(file_status s) noexcept;
 ```
 ```
 *Returns:* `is_regular_file(status(p))`.
 *Throws:* `filesystem_error` if `status(p)` would throw
+`filesystem_error`.
 ``` cpp
 bool is_regular_file(const path& p, error_code& ec) noexcept;
 ```
 between cases, call the `status` function directly. — *end note*]
 *Returns:* `is_regular_file(status(p, ec))`. Returns `false` if an error
 occurs.
+#### Is socket <a id="fs.op.is.socket">[[fs.op.is.socket]]</a>
 ``` cpp
 bool is_socket(file_status s) noexcept;
 ```
 respectively. The signature with argument `ec` returns `false` if an
 error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Is symlink <a id="fs.op.is.symlink">[[fs.op.is.symlink]]</a>
 ``` cpp
 bool is_symlink(file_status s) noexcept;
 ```
 `is_symlink(symlink_status(p, ec))`, respectively. The signature with
 argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Last write time <a id="fs.op.last.write.time">[[fs.op.last.write.time]]</a>
 ``` cpp
 file_time_type last_write_time(const path& p);
 file_time_type last_write_time(const path& p, error_code& ec) noexcept;
 ```
 *Returns:* The time of last data modification of `p`, determined as if
+by the value of the POSIX `stat` class member `st_mtime` obtained as if
+by POSIX `stat()`. The signature with argument `ec` returns
 `file_time_type::min()` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 ``` cpp
 void permissions(const path& p, perms prms, perm_options opts=perm_options::replace);
 void permissions(const path& p, perms prms, error_code& ec) noexcept;
 void permissions(const path& p, perms prms, perm_options opts, error_code& ec);
 ```
+*Preconditions:* Exactly one of the `perm_options` constants `replace`,
 `add`, or `remove` is present in `opts`.
 *Remarks:* The second signature behaves as if it had an additional
 parameter `perm_options` `opts` with an argument of
 `perm_options::replace`.
 or `path()` at the first error occurrence, if any.
 *Throws:* As specified in  [[fs.err.report]].
+#### Read symlink <a id="fs.op.read.symlink">[[fs.op.read.symlink]]</a>
 ``` cpp
 path read_symlink(const path& p);
 path read_symlink(const path& p, error_code& ec);
 ```
 as if by POSIX `remove()`.
 [*Note 1*: A symbolic link is itself removed, rather than the file it
 resolves to. — *end note*]
+*Ensures:* `exists(symlink_status(p))` is `false`.
 *Returns:* `false` if `p` did not exist, otherwise `true`. The signature
 with argument `ec` returns `false` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
+#### Remove all <a id="fs.op.remove.all">[[fs.op.remove.all]]</a>
 ``` cpp
 uintmax_t remove_all(const path& p);
+uintmax_t remove_all(const path& p, error_code& ec);
 ```
 *Effects:* Recursively deletes the contents of `p` if it exists, then
 deletes file `p` itself, as if by POSIX `remove()`.
 [*Note 1*: A symbolic link is itself removed, rather than the file it
 resolves to. — *end note*]
+*Ensures:* `exists(symlink_status(p))` is `false`.
 *Returns:* The number of files removed. The signature with argument `ec`
 returns `static_cast< uintmax_t>(-1)` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 — *end note*]
 *Throws:* As specified in  [[fs.err.report]].
+#### Resize file <a id="fs.op.resize.file">[[fs.op.resize.file]]</a>
 ``` cpp
 void resize_file(const path& p, uintmax_t new_size);
 void resize_file(const path& p, uintmax_t new_size, error_code& ec) noexcept;
 ```
+*Effects:* Causes the size that would be returned by `file_size(p)` to
+be equal to `new_size`, as if by POSIX `truncate()`.
 *Throws:* As specified in  [[fs.err.report]].
 #### Space <a id="fs.op.space">[[fs.op.space]]</a>
 ``` cpp
 space_info space(const path& p);
 space_info space(const path& p, error_code& ec) noexcept;
   - Otherwise, if the attributes indicate a fifo or pipe file, as if by
     POSIX `S_ISFIFO`, returns `file_status(file_type::fifo, prms)`.
   - Otherwise, if the attributes indicate a socket, as if by POSIX
     `S_ISSOCK`, returns `file_status(file_type::socket, prms)`.
   - Otherwise, if the attributes indicate an implementation-defined file
+    type [[fs.enum.file.type]], returns
     `file_status(file_type::`*`A`*`, prms)`, where *A* is the constant
     for the *implementation-defined* file type.
   - Otherwise, returns `file_status(file_type::unknown, prms)`.
 *Remarks:* If a symbolic link is encountered during pathname resolution,
 pathname resolution continues using the contents of the symbolic link.
+#### Status known <a id="fs.op.status.known">[[fs.op.status.known]]</a>
 ``` cpp
 bool status_known(file_status s) noexcept;
 ```
 *Returns:* `s.type() != file_type::none`.
+#### Symlink status <a id="fs.op.symlink.status">[[fs.op.symlink.status]]</a>
 ``` cpp
 file_status symlink_status(const path& p);
 file_status symlink_status(const path& p, error_code& ec) noexcept;
 ```
 *Remarks:* Pathname resolution terminates if `p` names a symbolic link.
 *Throws:* As specified in  [[fs.err.report]].
+#### Temporary directory path <a id="fs.op.temp.dir.path">[[fs.op.temp.dir.path]]</a>
 ``` cpp
 path temp_directory_path();
 path temp_directory_path(error_code& ec);
 ```
+Let `p` be an unspecified directory path suitable for temporary files.
+*Effects:* If `exists(p)` is `false` or `is_directory(p)` is `false`, an
+error is reported [[fs.err.report]].
+*Returns:* The path `p`. The signature with argument `ec` returns
 `path()` if an error occurs.
 *Throws:* As specified in  [[fs.err.report]].
 [*Example 1*: For POSIX-based operating systems, an implementation
 in the list TMPDIR, TMP, TEMP, TEMPDIR, or if none of these are found,
 `"/tmp"`. For Windows-based operating systems, an implementation might
 return the path reported by the Windows `GetTempPath` API
 function. — *end example*]
+#### Weakly canonical <a id="fs.op.weakly.canonical">[[fs.op.weakly.canonical]]</a>
 ``` cpp
 path weakly_canonical(const path& p);
 path weakly_canonical(const path& p, error_code& ec);
 ```
 *Returns:* `p` with symlinks resolved and the result
+normalized [[fs.path.generic]].
 *Effects:* Using `status(p)` or `status(p, ec)`, respectively, to
 determine existence, return a path composed by `operator/=` from the
+result of calling `canonical()` with a path argument composed of the
+leading elements of `p` that exist, if any, followed by the elements of
+`p` that do not exist, if any. For the first form, `canonical()` is
+called without an `error_code` argument. For the second form,
+`canonical()` is called with `ec` as an `error_code` argument, and
+`path()` is returned at the first error occurrence, if any.
+*Ensures:* The returned path is in normal form [[fs.path.generic]].
+*Remarks:* Implementations should avoid unnecessary normalization such
+as when `canonical` has already been called on the entirety of `p`.
 *Throws:* As specified in  [[fs.err.report]].
 ## C library files <a id="c.files">[[c.files]]</a>
 #define stdin see below
 #define stdout see below
 namespace std {
   int remove(const char* filename);
+  int rename(const char* old_p, const char* new_p);
   FILE* tmpfile();
   char* tmpnam(char* s);
   int fclose(FILE* stream);
   int fflush(FILE* stream);
   FILE* fopen(const char* filename, const char* mode);
 The contents and meaning of the header `<cstdio>` are the same as the C
 standard library header `<stdio.h>`.
 Calls to the function `tmpnam` with an argument that is a null pointer
+value may introduce a data race [[res.on.data.races]] with other calls
+to `tmpnam` with an argument that is a null pointer value.
+See also: ISO C 7.21
 ### Header `<cinttypes>` synopsis <a id="cinttypes.syn">[[cinttypes.syn]]</a>
 ``` cpp
 #include <cstdint>  // see [cstdint.syn]
 The contents and meaning of the header `<cinttypes>` are the same as the
 C standard library header `<inttypes.h>`, with the following changes:
 - The header `<cinttypes>` includes the header `<cstdint>` instead of
   `<stdint.h>`, and
+- if and only if the type `intmax_t` designates an extended integer type
+  [[basic.fundamental]], the following function signatures are added:
   ``` cpp
   intmax_t abs(intmax_t);
   imaxdiv_t div(intmax_t, intmax_t);
   ```
   which shall have the same semantics as the function signatures
   `intmax_t imaxabs(intmax_t)` and
   `imaxdiv_t imaxdiv(intmax_t, intmax_t)`, respectively.
+See also: ISO C 7.8
 <!-- Link reference definitions -->
 [adjustfield.manip]: #adjustfield.manip
 [basefield.manip]: #basefield.manip
 [basic.fundamental]: basic.md#basic.fundamental
 [basic.ios.cons]: #basic.ios.cons
+[basic.ios.copyfmt]: #basic.ios.copyfmt
 [basic.ios.members]: #basic.ios.members
 [basic.start.main]: basic.md#basic.start.main
 [bidirectional.iterators]: iterators.md#bidirectional.iterators
 [bitmask.types]: library.md#bitmask.types
 [c.files]: #c.files
+[char.traits]: strings.md#char.traits
 [cinttypes.syn]: #cinttypes.syn
+[container.requirements.general]: containers.md#container.requirements.general
+[cpp17.allocator]: #cpp17.allocator
+[cpp17.copyassignable]: #cpp17.copyassignable
+[cpp17.copyconstructible]: #cpp17.copyconstructible
+[cpp17.defaultconstructible]: #cpp17.defaultconstructible
+[cpp17.destructible]: #cpp17.destructible
+[cpp17.equalitycomparable]: #cpp17.equalitycomparable
 [cstdio.syn]: #cstdio.syn
 [defns.ntcts]: library.md#defns.ntcts
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 [filebuf]: #filebuf
 [filebuf.assign]: #filebuf.assign
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 [filebuf.members]: #filebuf.members
+[filebuf.open.modes]: #filebuf.open.modes
+[filebuf.seekoff]: #filebuf.seekoff
 [filebuf.virtuals]: #filebuf.virtuals
 [filesystems]: #filesystems
 [floatfield.manip]: #floatfield.manip
 [fmtflags.manip]: #fmtflags.manip
 [fmtflags.state]: #fmtflags.state
 [fpos]: #fpos
 [fpos.members]: #fpos.members
 [fpos.operations]: #fpos.operations
+[fs.class.directory.entry]: #fs.class.directory.entry
+[fs.class.directory.iterator]: #fs.class.directory.iterator
+[fs.class.file.status]: #fs.class.file.status
+[fs.class.filesystem.error]: #fs.class.filesystem.error
 [fs.class.path]: #fs.class.path
 [fs.class.rec.dir.itr]: #fs.class.rec.dir.itr
 [fs.conform.9945]: #fs.conform.9945
 [fs.conform.os]: #fs.conform.os
 [fs.conformance]: #fs.conformance
 [fs.dir.entry.cons]: #fs.dir.entry.cons
 [fs.dir.entry.mods]: #fs.dir.entry.mods
 [fs.dir.entry.obs]: #fs.dir.entry.obs
 [fs.dir.itr.members]: #fs.dir.itr.members
 [fs.dir.itr.nonmembers]: #fs.dir.itr.nonmembers
 [fs.enum]: #fs.enum
 [fs.enum.copy.opts]: #fs.enum.copy.opts
 [fs.enum.dir.opts]: #fs.enum.dir.opts
+[fs.enum.file.type]: #fs.enum.file.type
 [fs.enum.path.format]: #fs.enum.path.format
 [fs.enum.perm.opts]: #fs.enum.perm.opts
 [fs.enum.perms]: #fs.enum.perms
 [fs.err.report]: #fs.err.report
+[fs.file.status.cons]: #fs.file.status.cons
+[fs.file.status.mods]: #fs.file.status.mods
+[fs.file.status.obs]: #fs.file.status.obs
+[fs.filesystem.error.members]: #fs.filesystem.error.members
 [fs.filesystem.syn]: #fs.filesystem.syn
 [fs.general]: #fs.general
 [fs.norm.ref]: #fs.norm.ref
 [fs.op.absolute]: #fs.op.absolute
 [fs.op.canonical]: #fs.op.canonical
 [fs.op.copy]: #fs.op.copy
+[fs.op.copy.file]: #fs.op.copy.file
+[fs.op.copy.symlink]: #fs.op.copy.symlink
+[fs.op.create.dir.symlk]: #fs.op.create.dir.symlk
+[fs.op.create.directories]: #fs.op.create.directories
+[fs.op.create.directory]: #fs.op.create.directory
+[fs.op.create.hard.lk]: #fs.op.create.hard.lk
+[fs.op.create.symlink]: #fs.op.create.symlink
+[fs.op.current.path]: #fs.op.current.path
 [fs.op.equivalent]: #fs.op.equivalent
 [fs.op.exists]: #fs.op.exists
+[fs.op.file.size]: #fs.op.file.size
 [fs.op.funcs]: #fs.op.funcs
+[fs.op.hard.lk.ct]: #fs.op.hard.lk.ct
+[fs.op.is.block.file]: #fs.op.is.block.file
+[fs.op.is.char.file]: #fs.op.is.char.file
+[fs.op.is.directory]: #fs.op.is.directory
+[fs.op.is.empty]: #fs.op.is.empty
+[fs.op.is.fifo]: #fs.op.is.fifo
+[fs.op.is.other]: #fs.op.is.other
+[fs.op.is.regular.file]: #fs.op.is.regular.file
+[fs.op.is.socket]: #fs.op.is.socket
+[fs.op.is.symlink]: #fs.op.is.symlink
+[fs.op.last.write.time]: #fs.op.last.write.time
 [fs.op.permissions]: #fs.op.permissions
 [fs.op.proximate]: #fs.op.proximate
+[fs.op.read.symlink]: #fs.op.read.symlink
 [fs.op.relative]: #fs.op.relative
 [fs.op.remove]: #fs.op.remove
+[fs.op.remove.all]: #fs.op.remove.all
 [fs.op.rename]: #fs.op.rename
+[fs.op.resize.file]: #fs.op.resize.file
 [fs.op.space]: #fs.op.space
 [fs.op.status]: #fs.op.status
+[fs.op.status.known]: #fs.op.status.known
+[fs.op.symlink.status]: #fs.op.symlink.status
+[fs.op.temp.dir.path]: #fs.op.temp.dir.path
+[fs.op.weakly.canonical]: #fs.op.weakly.canonical
 [fs.path.append]: #fs.path.append
 [fs.path.assign]: #fs.path.assign
 [fs.path.compare]: #fs.path.compare
 [fs.path.concat]: #fs.path.concat
 [fs.path.construct]: #fs.path.construct
 [fs.path.cvt]: #fs.path.cvt
 [fs.path.decompose]: #fs.path.decompose
 [fs.path.fmt.cvt]: #fs.path.fmt.cvt
 [fs.path.gen]: #fs.path.gen
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 [fs.path.generic.obs]: #fs.path.generic.obs
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 [ifstream.members]: #ifstream.members
 [input.iterators]: iterators.md#input.iterators
 [input.output]: #input.output
 [input.output.general]: #input.output.general
 [input.streams]: #input.streams
+[intro.multithread]: basic.md#intro.multithread
+[intro.races]: basic.md#intro.races
 [iomanip.syn]: #iomanip.syn
 [ios]: #ios
 [ios.base]: #ios.base
 [ios.base.callback]: #ios.base.callback
 [ios.base.cons]: #ios.base.cons
 [ios.base.locales]: #ios.base.locales
 [ios.base.storage]: #ios.base.storage
+[ios.failure]: #ios.failure
+[ios.fmtflags]: #ios.fmtflags
+[ios.fmtflags.const]: #ios.fmtflags.const
+[ios.init]: #ios.init
+[ios.iostate]: #ios.iostate
 [ios.members.static]: #ios.members.static
+[ios.openmode]: #ios.openmode
 [ios.overview]: #ios.overview
+[ios.seekdir]: #ios.seekdir
 [ios.syn]: #ios.syn
 [ios.types]: #ios.types
 [iosfwd.syn]: #iosfwd.syn
 [iostate.flags]: #iostate.flags
 [iostream.assign]: #iostream.assign
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 [iostream.dest]: #iostream.dest
 [iostream.syn]: #iostream.syn
 [iostreamclass]: #iostreamclass
 [iostreams.base]: #iostreams.base
 [iostreams.limits.pos]: #iostreams.limits.pos
 [iostreams.requirements]: #iostreams.requirements
+[iostreams.summary]: #iostreams.summary
 [iostreams.threadsafety]: #iostreams.threadsafety
 [istream]: #istream
 [istream.assign]: #istream.assign
 [istream.cons]: #istream.cons
 [istream.extractors]: #istream.extractors
 [istream.formatted]: #istream.formatted
 [istream.formatted.arithmetic]: #istream.formatted.arithmetic
 [istream.formatted.reqmts]: #istream.formatted.reqmts
 [istream.manip]: #istream.manip
 [istream.rvalue]: #istream.rvalue
+[istream.sentry]: #istream.sentry
 [istream.syn]: #istream.syn
 [istream.unformatted]: #istream.unformatted
 [istringstream]: #istringstream
 [istringstream.assign]: #istringstream.assign
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 [lex.charset]: lex.md#lex.charset
 [locale.codecvt.virtuals]: localization.md#locale.codecvt.virtuals
 [locale.num.get]: localization.md#locale.num.get
+[namespace.std]: library.md#namespace.std
 [narrow.stream.objects]: #narrow.stream.objects
+[numeric.limits]: support.md#numeric.limits
 [ofstream]: #ofstream
 [ofstream.assign]: #ofstream.assign
 [ofstream.cons]: #ofstream.cons
 [ofstream.members]: #ofstream.members
 [ostream]: #ostream
 [ostream.inserters.arithmetic]: #ostream.inserters.arithmetic
 [ostream.inserters.character]: #ostream.inserters.character
 [ostream.manip]: #ostream.manip
 [ostream.rvalue]: #ostream.rvalue
 [ostream.seeks]: #ostream.seeks
+[ostream.sentry]: #ostream.sentry
 [ostream.syn]: #ostream.syn
 [ostream.unformatted]: #ostream.unformatted
 [ostringstream]: #ostringstream
 [ostringstream.assign]: #ostringstream.assign
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 [string.streams]: #string.streams
 [stringbuf]: #stringbuf
 [stringbuf.assign]: #stringbuf.assign
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+[stringbuf.seekoff.newoff]: #stringbuf.seekoff.newoff
+[stringbuf.seekoff.pos]: #stringbuf.seekoff.pos
 [stringbuf.virtuals]: #stringbuf.virtuals
 [strings]: strings.md#strings
 [stringstream]: #stringstream
 [stringstream.assign]: #stringstream.assign
 [stringstream.cons]: #stringstream.cons
 [stringstream.members]: #stringstream.members
+[syncstream]: #syncstream
+[syncstream.osyncstream]: #syncstream.osyncstream
+[syncstream.osyncstream.cons]: #syncstream.osyncstream.cons
+[syncstream.osyncstream.members]: #syncstream.osyncstream.members
+[syncstream.osyncstream.overview]: #syncstream.osyncstream.overview
+[syncstream.syn]: #syncstream.syn
+[syncstream.syncbuf]: #syncstream.syncbuf
+[syncstream.syncbuf.assign]: #syncstream.syncbuf.assign
+[syncstream.syncbuf.cons]: #syncstream.syncbuf.cons
+[syncstream.syncbuf.members]: #syncstream.syncbuf.members
+[syncstream.syncbuf.overview]: #syncstream.syncbuf.overview
+[syncstream.syncbuf.special]: #syncstream.syncbuf.special
+[syncstream.syncbuf.virtuals]: #syncstream.syncbuf.virtuals
 [temp.deduct]: temp.md#temp.deduct
 [wide.stream.objects]: #wide.stream.objects
 [^1]: It is the implementation’s responsibility to implement headers so
     that including `<iosfwd>` and other headers does not violate the
     rules about multiple occurrences of default arguments.
+[^2]: If it is possible for them to do so, implementations should
+    initialize the objects earlier than required.
+[^3]: Constructors and destructors for objects with static storage
+ duration can access these objects to read input from `stdin` or
+ write output to `stdout` or `stderr`.
 [^4]: Typically `long long`.
 [^5]: `streamsize` is used in most places where ISO C would use
+    `size_t`.
 [^6]: This implies that operations on a standard iostream object can be
     mixed arbitrarily with operations on the corresponding stdio stream.
     In practical terms, synchronization usually means that a standard
     iostream object and a standard stdio object share a buffer.
 [^7]: An implementation is free to implement both the integer array
     pointed at by `iarray` and the pointer array pointed at by `parray`
     as sparse data structures, possibly with a one-element cache for
     each.
+[^8]: For example, because it cannot allocate space.
+[^9]: For example, because it cannot allocate space.
 [^10]: This suggests an infinite amount of copying, but the
     implementation can keep track of the maximum element of the arrays
     that is nonzero.
 [^18]: This will be possible only in functions that are part of the
     library. The semantics of the constructor used in user code is as
     specified.
+[^19]: The `sentry` constructor and destructor can also perform
+ additional implementation-dependent operations.
+[^20]: This is done without causing an `ios_base::failure` to be thrown.
 [^21]: See, for example, the function signature
+    `ws(basic_istream&)`[[istream.manip]].
 [^22]: See, for example, the function signature
+    `dec(ios_base&)`[[basefield.manip]].
+[^23]: This is done without causing an `ios_base::failure` to be thrown.
 [^24]: Note that this function is not overloaded on types `signed char`
     and `unsigned char`.
 [^25]: Note that this function is not overloaded on types `signed char`
     function can determine that no synchronization is necessary.
 [^32]: The `sentry` constructor and destructor can also perform
     additional implementation-dependent operations.
+[^33]: without causing an `ios_base::failure` to be thrown.
 [^34]: See, for example, the function signature
+    `endl(basic_ostream&)`[[ostream.manip]].
 [^35]: See, for example, the function signature
+    `dec(ios_base&)`[[basefield.manip]].
+[^36]: without causing an `ios_base::failure` to be thrown.
 [^37]: Note that this function is not overloaded on types `signed char`
     and `unsigned char`.
 [^38]: Note that this function is not overloaded on types `signed char`
     `basic_ostream<charT, traits>` object `cout` (the same as
     `cout << noshowbase`).
 [^40]: The macro `SEEK_END` is defined, and the function signatures
     `fopen(const char*, const char*)` and `fseek(FILE*, long, int)` are
+    declared, in `<cstdio>`.
 [^41]: POSIX® is a registered trademark of The IEEE. Windows® is a
     registered trademark of Microsoft Corporation. This information is
     given for the convenience of users of this document and does not
     constitute an endorsement by ISO or IEC of these products.

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