diff --git a/Doc/c-api/exceptions.rst b/Doc/c-api/exceptions.rst
index 2bc1bd8..dd1e026 100644
--- a/Doc/c-api/exceptions.rst
+++ b/Doc/c-api/exceptions.rst
@@ -186,34 +186,42 @@
    then it constructs a tuple object whose first item is the *ierr* value and whose
    second item is the corresponding error message (gotten from
    :c:func:`FormatMessage`), and then calls ``PyErr_SetObject(PyExc_WindowsError,
-   object)``. This function always returns *NULL*. Availability: Windows.
+   object)``. This function always returns *NULL*.
+
+   .. availability:: Windows.
 
 
 .. c:function:: PyObject* PyErr_SetExcFromWindowsErr(PyObject *type, int ierr)
 
    Similar to :c:func:`PyErr_SetFromWindowsErr`, with an additional parameter
-   specifying the exception type to be raised. Availability: Windows.
+   specifying the exception type to be raised.
+
+   .. availability:: Windows.
 
 
 .. c:function:: PyObject* PyErr_SetFromWindowsErrWithFilename(int ierr, const char *filename)
 
    Similar to :c:func:`PyErr_SetFromWindowsErrWithFilenameObject`, but the
    filename is given as a C string.  *filename* is decoded from the filesystem
-   encoding (:func:`os.fsdecode`).  Availability: Windows.
+   encoding (:func:`os.fsdecode`).
+
+   .. availability:: Windows.
 
 
 .. c:function:: PyObject* PyErr_SetExcFromWindowsErrWithFilenameObject(PyObject *type, int ierr, PyObject *filename)
 
    Similar to :c:func:`PyErr_SetFromWindowsErrWithFilenameObject`, with an
    additional parameter specifying the exception type to be raised.
-   Availability: Windows.
+
+   .. availability:: Windows.
 
 
 .. c:function:: PyObject* PyErr_SetExcFromWindowsErrWithFilenameObjects(PyObject *type, int ierr, PyObject *filename, PyObject *filename2)
 
    Similar to :c:func:`PyErr_SetExcFromWindowsErrWithFilenameObject`,
    but accepts a second filename object.
-   Availability: Windows.
+
+   .. availability:: Windows.
 
    .. versionadded:: 3.4
 
@@ -221,7 +229,9 @@
 .. c:function:: PyObject* PyErr_SetExcFromWindowsErrWithFilename(PyObject *type, int ierr, const char *filename)
 
    Similar to :c:func:`PyErr_SetFromWindowsErrWithFilename`, with an additional
-   parameter specifying the exception type to be raised. Availability: Windows.
+   parameter specifying the exception type to be raised.
+
+   .. availability:: Windows.
 
 
 .. c:function:: PyObject* PyErr_SetImportError(PyObject *msg, PyObject *name, PyObject *path)
diff --git a/Doc/c-api/init.rst b/Doc/c-api/init.rst
index e51a255..6b5290a 100644
--- a/Doc/c-api/init.rst
+++ b/Doc/c-api/init.rst
@@ -156,7 +156,7 @@
 
    See :pep:`529` for more details.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
 .. c:var:: Py_LegacyWindowsStdioFlag
 
@@ -168,7 +168,7 @@
 
    See :pep:`528` for more details.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
 .. c:var:: Py_NoSiteFlag
 
diff --git a/Doc/library/_thread.rst b/Doc/library/_thread.rst
index 67cb709..acffabf 100644
--- a/Doc/library/_thread.rst
+++ b/Doc/library/_thread.rst
@@ -101,7 +101,8 @@
    memory page size - platform documentation should be referred to for more
    information (4 KiB pages are common; using multiples of 4096 for the stack size is
    the suggested approach in the absence of more specific information).
-   Availability: Windows, systems with POSIX threads.
+
+   .. availability:: Windows, systems with POSIX threads.
 
 
 .. data:: TIMEOUT_MAX
diff --git a/Doc/library/asyncio-eventloop.rst b/Doc/library/asyncio-eventloop.rst
index 76c8ce9..96f5e0b 100644
--- a/Doc/library/asyncio-eventloop.rst
+++ b/Doc/library/asyncio-eventloop.rst
@@ -510,7 +510,7 @@
    See the documentation of the :meth:`loop.create_connection` method
    for information about arguments to this method.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.7
 
@@ -630,7 +630,7 @@
    See the documentation of the :meth:`loop.create_server` method
    for information about arguments to this method.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.7
 
@@ -979,7 +979,7 @@
    Return ``True`` if the signal handler was removed, or ``False`` if
    no handler was set for the given signal.
 
-Availability: Unix.
+   .. availability:: Unix.
 
 .. seealso::
 
@@ -1423,14 +1423,14 @@
       asyncio.set_event_loop(loop)
 
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
 
 .. class:: ProactorEventLoop
 
    An event loop for Windows that uses "I/O Completion Ports" (IOCP).
 
-   Availability: Windows.
+   .. availability:: Windows.
 
    .. seealso::
 
diff --git a/Doc/library/asyncio-policy.rst b/Doc/library/asyncio-policy.rst
index 560f8b3..82c8382 100644
--- a/Doc/library/asyncio-policy.rst
+++ b/Doc/library/asyncio-policy.rst
@@ -107,7 +107,7 @@
    An alternative event loop policy that uses the
    :class:`SelectorEventLoop` event loop implementation.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
 
 .. class:: WindowsProactorEventLoopPolicy
@@ -115,7 +115,7 @@
    An alternative event loop policy that uses the
    :class:`ProactorEventLoop` event loop implementation.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
 
 Process Watchers
diff --git a/Doc/library/asyncio-stream.rst b/Doc/library/asyncio-stream.rst
index 60aae16..e686a6a 100644
--- a/Doc/library/asyncio-stream.rst
+++ b/Doc/library/asyncio-stream.rst
@@ -114,7 +114,7 @@
 
    See also the documentation of :meth:`loop.create_unix_connection`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.7
 
@@ -136,7 +136,7 @@
 
    See also the documentation of :meth:`loop.create_unix_server`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.7
 
diff --git a/Doc/library/asyncore.rst b/Doc/library/asyncore.rst
index 11d3616..a86518e 100644
--- a/Doc/library/asyncore.rst
+++ b/Doc/library/asyncore.rst
@@ -273,14 +273,18 @@
    with an optional map argument and wraps it for use with the :c:func:`poll`
    or :c:func:`loop` functions.  If provided a file object or anything with a
    :c:func:`fileno` method, that method will be called and passed to the
-   :class:`file_wrapper` constructor.  Availability: UNIX.
+   :class:`file_wrapper` constructor.
+
+   .. availability:: Unix.
 
 .. class:: file_wrapper()
 
    A file_wrapper takes an integer file descriptor and calls :func:`os.dup` to
    duplicate the handle so that the original handle may be closed independently
    of the file_wrapper.  This class implements sufficient methods to emulate a
-   socket for use by the :class:`file_dispatcher` class.  Availability: UNIX.
+   socket for use by the :class:`file_dispatcher` class.
+
+   .. availability:: Unix.
 
 
 .. _asyncore-example-1:
diff --git a/Doc/library/codecs.rst b/Doc/library/codecs.rst
index 24008a0..b9c04c2 100644
--- a/Doc/library/codecs.rst
+++ b/Doc/library/codecs.rst
@@ -1471,7 +1471,7 @@
 
 Encode operand according to the ANSI codepage (CP_ACP).
 
-Availability: Windows only.
+.. availability:: Windows only.
 
 .. versionchanged:: 3.3
    Support any error handler.
diff --git a/Doc/library/hashlib.rst b/Doc/library/hashlib.rst
index 4a8d705..a16c7cd 100644
--- a/Doc/library/hashlib.rst
+++ b/Doc/library/hashlib.rst
@@ -271,7 +271,7 @@
    factor and *maxmem* limits memory (OpenSSL 1.1.0 defaults to 32 MiB).
    *dklen* is the length of the derived key.
 
-   Availability: OpenSSL 1.1+
+   .. availability:: OpenSSL 1.1+.
 
    .. versionadded:: 3.6
 
diff --git a/Doc/library/intro.rst b/Doc/library/intro.rst
index e3283ca..8567e4d 100644
--- a/Doc/library/intro.rst
+++ b/Doc/library/intro.rst
@@ -47,3 +47,16 @@
 
 Let the show begin!
 
+
+.. _availability:
+
+Notes on availability
+=====================
+
+* An "Availability: Unix" note means that this function is commonly found on
+  Unix systems.  It does not make any claims about its existence on a specific
+  operating system.
+
+* If not separately noted, all functions that claim "Availability: Unix" are
+  supported on Mac OS X, which builds on a Unix core.
+
diff --git a/Doc/library/mimetypes.rst b/Doc/library/mimetypes.rst
index 973014a..5728407 100644
--- a/Doc/library/mimetypes.rst
+++ b/Doc/library/mimetypes.rst
@@ -260,7 +260,9 @@
 
    .. method:: MimeTypes.read_windows_registry(strict=True)
 
-      Load MIME type information from the Windows registry.  Availability: Windows.
+      Load MIME type information from the Windows registry.
+
+      .. availability:: Windows.
 
       If *strict* is ``True``, information will be added to the list of standard
       types, else to the list of non-standard types.
diff --git a/Doc/library/os.path.rst b/Doc/library/os.path.rst
index 5a0b178..f68fe61 100644
--- a/Doc/library/os.path.rst
+++ b/Doc/library/os.path.rst
@@ -93,7 +93,7 @@
    pathnames, or if *paths* is empty.  Unlike :func:`commonprefix`, this
    returns a valid path.
 
-   Availability: Unix, Windows
+   .. availability:: Unix, Windows.
 
    .. versionadded:: 3.5
 
@@ -357,7 +357,7 @@
 
    *start* defaults to :attr:`os.curdir`.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.
@@ -369,7 +369,7 @@
    This is determined by the device number and i-node number and raises an
    exception if an :func:`os.stat` call on either pathname fails.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.2
       Added Windows support.
@@ -385,7 +385,7 @@
 
    Return ``True`` if the file descriptors *fp1* and *fp2* refer to the same file.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.2
       Added Windows support.
@@ -401,7 +401,7 @@
    :func:`os.lstat`, or :func:`os.stat`.  This function implements the
    underlying comparison used by :func:`samefile` and :func:`sameopenfile`.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.4
       Added Windows support.
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index bc8d5a8..75d473c 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -32,15 +32,6 @@
   objects, and result in an object of the same type, if a path or file name is
   returned.
 
-* An "Availability: Unix" note means that this function is commonly found on
-  Unix systems.  It does not make any claims about its existence on a specific
-  operating system.
-
-* If not separately noted, all functions that claim "Availability: Unix" are
-  supported on Mac OS X, which builds on a Unix core.
-
-.. Availability notes get their own line and occur at the end of the function
-.. documentation.
 
 .. note::
 
@@ -105,7 +96,7 @@
 
    Return the filename corresponding to the controlling terminal of the process.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: environ
@@ -235,7 +226,7 @@
    and ``'surrogateescape'`` error handler. Use :func:`os.getenvb` if you
    would like to use a different encoding.
 
-   Availability: most flavors of Unix, Windows.
+   .. availability:: most flavors of Unix, Windows.
 
 
 .. function:: getenvb(key, default=None)
@@ -246,7 +237,7 @@
    :func:`getenvb` is only available if :data:`supports_bytes_environ`
    is True.
 
-   Availability: most flavors of Unix.
+   .. availability:: most flavors of Unix.
 
    .. versionadded:: 3.2
 
@@ -267,7 +258,7 @@
    Return the effective group id of the current process.  This corresponds to the
    "set id" bit on the file being executed in the current process.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: geteuid()
@@ -276,7 +267,7 @@
 
    Return the current process's effective user id.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: getgid()
@@ -285,7 +276,7 @@
 
    Return the real group id of the current process.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: getgrouplist(user, group)
@@ -294,7 +285,7 @@
    list, it is included; typically, *group* is specified as the group ID
    field from the password record for *user*.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -303,7 +294,7 @@
 
    Return list of supplemental group ids associated with the current process.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. note::
 
@@ -331,7 +322,7 @@
    falls back to ``pwd.getpwuid(os.getuid())[0]`` to get the login name of the
    current real user id.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
 
 .. function:: getpgid(pid)
@@ -339,7 +330,7 @@
    Return the process group id of the process with process id *pid*. If *pid* is 0,
    the process group id of the current process is returned.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 .. function:: getpgrp()
 
@@ -347,7 +338,7 @@
 
    Return the id of the current process group.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: getpid()
@@ -365,7 +356,7 @@
    the id returned is the one of the init process (1), on Windows it is still
    the same id, which may be already reused by another process.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.2
       Added support for Windows.
@@ -383,7 +374,7 @@
    (respectively) the calling process, the process group of the calling process,
    or the real user ID of the calling process.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -394,7 +385,7 @@
 
    Parameters for the :func:`getpriority` and :func:`setpriority` functions.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -404,7 +395,7 @@
    Return a tuple (ruid, euid, suid) denoting the current process's
    real, effective, and saved user ids.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.2
 
@@ -414,7 +405,7 @@
    Return a tuple (rgid, egid, sgid) denoting the current process's
    real, effective, and saved group ids.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.2
 
@@ -425,7 +416,7 @@
 
    Return the current process's real user id.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: initgroups(username, gid)
@@ -434,7 +425,7 @@
    the groups of which the specified username is a member, plus the specified
    group id.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.2
 
@@ -447,7 +438,7 @@
    changes to the environment affect subprocesses started with :func:`os.system`,
    :func:`popen` or :func:`fork` and :func:`execv`.
 
-   Availability: most flavors of Unix, Windows.
+   .. availability:: most flavors of Unix, Windows.
 
    .. note::
 
@@ -464,21 +455,21 @@
 
    Set the current process's effective group id.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: seteuid(euid)
 
    Set the current process's effective user id.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: setgid(gid)
 
    Set the current process' group id.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: setgroups(groups)
@@ -487,7 +478,7 @@
    *groups*. *groups* must be a sequence, and each element must be an integer
    identifying a group. This operation is typically available only to the superuser.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. note:: On Mac OS X, the length of *groups* may not exceed the
       system-defined maximum number of effective group ids, typically 16.
@@ -499,7 +490,7 @@
    Call the system call :c:func:`setpgrp` or ``setpgrp(0, 0)`` depending on
    which version is implemented (if any).  See the Unix manual for the semantics.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: setpgid(pid, pgrp)
@@ -508,7 +499,7 @@
    process with id *pid* to the process group with id *pgrp*.  See the Unix manual
    for the semantics.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: setpriority(which, who, priority)
@@ -525,7 +516,7 @@
    *priority* is a value in the range -20 to 19. The default priority is 0;
    lower priorities cause more favorable scheduling.
 
-   Availability: Unix
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -534,14 +525,14 @@
 
    Set the current process's real and effective group ids.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: setresgid(rgid, egid, sgid)
 
    Set the current process's real, effective, and saved group ids.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.2
 
@@ -550,7 +541,7 @@
 
    Set the current process's real, effective, and saved user ids.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.2
 
@@ -559,21 +550,21 @@
 
    Set the current process's real and effective user ids.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: getsid(pid)
 
    Call the system call :c:func:`getsid`.  See the Unix manual for the semantics.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: setsid()
 
    Call the system call :c:func:`setsid`.  See the Unix manual for the semantics.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: setuid(uid)
@@ -582,7 +573,7 @@
 
    Set the current process's user id.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. placed in this section since it relates to errno.... a little weak
@@ -631,7 +622,7 @@
    :func:`socket.gethostname`  or even
    ``socket.gethostbyaddr(socket.gethostname())``.
 
-   Availability: recent flavors of Unix.
+   .. availability:: recent flavors of Unix.
 
    .. versionchanged:: 3.3
       Return type changed from a tuple to a tuple-like object
@@ -651,7 +642,7 @@
    calls to :func:`unsetenv` don't update ``os.environ``, so it is actually
    preferable to delete items of ``os.environ``.
 
-   Availability: most flavors of Unix, Windows.
+   .. availability:: most flavors of Unix, Windows.
 
 
 .. _os-newstreams:
@@ -754,7 +745,7 @@
    docs for :func:`chmod` for possible values of *mode*.  As of Python 3.3, this
    is equivalent to ``os.chmod(fd, mode)``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: fchown(fd, uid, gid)
@@ -764,7 +755,7 @@
    :func:`chown`.  As of Python 3.3, this is equivalent to ``os.chown(fd, uid,
    gid)``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: fdatasync(fd)
@@ -772,7 +763,7 @@
    Force write of file with filedescriptor *fd* to disk. Does not force update of
    metadata.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. note::
       This function is not available on MacOS.
@@ -795,7 +786,7 @@
 
    As of Python 3.3, this is equivalent to ``os.pathconf(fd, name)``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: fstat(fd)
@@ -816,7 +807,7 @@
    file descriptor *fd*, like :func:`statvfs`.  As of Python 3.3, this is
    equivalent to ``os.statvfs(fd)``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: fsync(fd)
@@ -828,7 +819,7 @@
    ``f.flush()``, and then do ``os.fsync(f.fileno())``, to ensure that all internal
    buffers associated with *f* are written to disk.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
 
 .. function:: ftruncate(fd, length)
@@ -837,7 +828,7 @@
    most *length* bytes in size.  As of Python 3.3, this is equivalent to
    ``os.truncate(fd, length)``.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.5
       Added support for Windows
@@ -849,7 +840,7 @@
 
    See also :func:`set_blocking` and :meth:`socket.socket.setblocking`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.5
 
@@ -867,7 +858,7 @@
    :data:`F_ULOCK` or :data:`F_TEST`.
    *len* specifies the section of the file to lock.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -879,7 +870,7 @@
 
    Flags that specify what action :func:`lockf` will take.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1011,7 +1002,7 @@
    descriptors are :ref:`non-inheritable <fd_inheritance>`. For a (slightly) more
    portable approach, use the :mod:`pty` module.
 
-   Availability: some flavors of Unix.
+   .. availability:: some flavors of Unix.
 
    .. versionchanged:: 3.4
       The new file descriptors are now non-inheritable.
@@ -1023,7 +1014,7 @@
    reading and writing, respectively. The new file descriptor is
    :ref:`non-inheritable <fd_inheritance>`.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.4
       The new file descriptors are now non-inheritable.
@@ -1037,7 +1028,7 @@
    Return a pair of file descriptors ``(r, w)`` usable for reading and writing,
    respectively.
 
-   Availability: some flavors of Unix.
+   .. availability:: some flavors of Unix.
 
    .. versionadded:: 3.3
 
@@ -1047,7 +1038,7 @@
    Ensures that enough disk space is allocated for the file specified by *fd*
    starting from *offset* and continuing for *len* bytes.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1062,7 +1053,7 @@
    :data:`POSIX_FADV_RANDOM`, :data:`POSIX_FADV_NOREUSE`,
    :data:`POSIX_FADV_WILLNEED` or :data:`POSIX_FADV_DONTNEED`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1077,7 +1068,7 @@
    Flags that can be used in *advice* in :func:`posix_fadvise` that specify
    the access pattern that is likely to be used.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1090,7 +1081,7 @@
    Return a bytestring containing the bytes read. If the end of the file
    referred to by *fd* has been reached, an empty bytes object is returned.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1116,8 +1107,8 @@
 
    Combine the functionality of :func:`os.readv` and :func:`os.pread`.
 
-   Availability: Linux 2.6.30 and newer, FreeBSD 6.0 and newer,
-   OpenBSD 2.7 and newer. Using flags requires Linux 4.6 or newer.
+   .. availability:: Linux 2.6.30 and newer, FreeBSD 6.0 and newer,
+      OpenBSD 2.7 and newer. Using flags requires Linux 4.6 or newer.
 
    .. versionadded:: 3.7
 
@@ -1132,7 +1123,7 @@
    If no bytes were read, it will return ``-1`` and set errno to
    :data:`errno.EAGAIN`.
 
-   Availability: Linux 4.14 and newer.
+   .. availability:: Linux 4.14 and newer.
 
    .. versionadded:: 3.7
 
@@ -1146,7 +1137,7 @@
    Currently, on Linux, this feature is usable only on a file descriptor opened
    using the :data:`O_DIRECT` flag.
 
-   Availability: Linux 4.6 and newer.
+   .. availability:: Linux 4.6 and newer.
 
    .. versionadded:: 3.7
 
@@ -1158,7 +1149,7 @@
 
    Return the number of bytes actually written.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1184,8 +1175,8 @@
 
    Combine the functionality of :func:`os.writev` and :func:`os.pwrite`.
 
-   Availability: Linux 2.6.30 and newer, FreeBSD 6.0 and newer,
-   OpenBSD 2.7 and newer. Using flags requires Linux 4.7 or newer.
+   .. availability:: Linux 2.6.30 and newer, FreeBSD 6.0 and newer,
+      OpenBSD 2.7 and newer. Using flags requires Linux 4.7 or newer.
 
    .. versionadded:: 3.7
 
@@ -1195,7 +1186,7 @@
    Provide a per-write equivalent of the :data:`O_DSYNC` ``open(2)`` flag. This
    flag effect applies only to the data range written by the system call.
 
-   Availability: Linux 4.7 and newer.
+   .. availability:: Linux 4.7 and newer.
 
    .. versionadded:: 3.7
 
@@ -1205,7 +1196,7 @@
    Provide a per-write equivalent of the :data:`O_SYNC` ``open(2)`` flag. This
    flag effect applies only to the data range written by the system call.
 
-   Availability: Linux 4.7 and newer.
+   .. availability:: Linux 4.7 and newer.
 
    .. versionadded:: 3.7
 
@@ -1257,7 +1248,7 @@
    Cross-platform applications should not use *headers*, *trailers* and *flags*
    arguments.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. note::
 
@@ -1274,7 +1265,7 @@
 
    See also :func:`get_blocking` and :meth:`socket.socket.setblocking`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.5
 
@@ -1286,7 +1277,7 @@
    Parameters to the :func:`sendfile` function, if the implementation supports
    them.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1304,7 +1295,7 @@
    The operating system may set a limit (:func:`sysconf` value
    ``'SC_IOV_MAX'``) on the number of buffers that can be used.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1314,7 +1305,7 @@
    Return the process group associated with the terminal given by *fd* (an open
    file descriptor as returned by :func:`os.open`).
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: tcsetpgrp(fd, pg)
@@ -1322,7 +1313,7 @@
    Set the process group associated with the terminal given by *fd* (an open file
    descriptor as returned by :func:`os.open`) to *pg*.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: ttyname(fd)
@@ -1331,7 +1322,7 @@
    file descriptor *fd*.  If *fd* is not associated with a terminal device, an
    exception is raised.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: write(fd, str)
@@ -1366,7 +1357,7 @@
    The operating system may set a limit (:func:`sysconf` value
    ``'SC_IOV_MAX'``) on the number of buffers that can be used.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1393,7 +1384,7 @@
    should normally be used, ``os.get_terminal_size`` is the low-level
    implementation.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
 .. class:: terminal_size
 
@@ -1442,13 +1433,13 @@
 
    Get the "inheritable" flag of the specified handle (a boolean).
 
-   Availability: Windows.
+   .. availability:: Windows.
 
 .. function:: set_handle_inheritable(handle, inheritable)
 
    Set the "inheritable" flag of the specified handle.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
 
 .. _os-file-dir:
@@ -1603,7 +1594,7 @@
 
    This function can support :ref:`not following symlinks <follow_symlinks>`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
       The *follow_symlinks* argument.
@@ -1668,7 +1659,7 @@
    See :func:`shutil.chown` for a higher-level function that accepts names in
    addition to numeric ids.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
       Added support for specifying an open file descriptor for *path*,
@@ -1682,7 +1673,7 @@
 
    Change the root directory of the current process to *path*.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.
@@ -1694,7 +1685,7 @@
    descriptor *fd*.  The descriptor must refer to an opened directory, not an
    open file.  As of Python 3.3, this is equivalent to ``os.chdir(fd)``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: getcwd()
@@ -1713,7 +1704,7 @@
    not follow symbolic links.  As of Python 3.3, this is equivalent to
    ``os.chflags(path, flags, follow_symlinks=False)``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.
@@ -1726,7 +1717,7 @@
    for possible values of *mode*.  As of Python 3.3, this is equivalent to
    ``os.chmod(path, mode, follow_symlinks=False)``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.
@@ -1737,7 +1728,7 @@
    function will not follow symbolic links.  As of Python 3.3, this is equivalent
    to ``os.chown(path, uid, gid, follow_symlinks=False)``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.
@@ -1751,7 +1742,7 @@
    supply :ref:`paths relative to directory descriptors <dir_fd>`, and :ref:`not
    following symlinks <follow_symlinks>`.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.2
       Added Windows support.
@@ -1909,7 +1900,7 @@
    FIFO for reading, and the client opens it for writing.  Note that :func:`mkfifo`
    doesn't open the FIFO --- it just creates the rendezvous point.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
       The *dir_fd* argument.
@@ -1931,7 +1922,7 @@
    This function can also support :ref:`paths relative to directory descriptors
    <dir_fd>`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
       The *dir_fd* argument.
@@ -1975,7 +1966,7 @@
    This function can support :ref:`specifying a file descriptor
    <path_fd>`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.
@@ -1987,7 +1978,7 @@
    the integer values defined for those names by the host operating system.  This
    can be used to determine the set of names known to the system.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: readlink(path, *, dir_fd=None)
@@ -2005,7 +1996,7 @@
    This function can also support :ref:`paths relative to directory descriptors
    <dir_fd>`.
 
-   Availability: Unix, Windows
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.2
       Added support for Windows 6.0 (Vista) symbolic links.
@@ -2596,7 +2587,7 @@
 
    This function can support :ref:`specifying a file descriptor <path_fd>`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionchanged:: 3.2
       The :const:`ST_RDONLY` and :const:`ST_NOSUID` constants were added.
@@ -2726,7 +2717,7 @@
       :exc:`OSError` is raised when the function is called by an unprivileged
       user.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.2
       Added support for Windows 6.0 (Vista) symbolic links.
@@ -2743,7 +2734,7 @@
 
    Force write of everything to disk.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -2755,7 +2746,7 @@
 
    This function can support :ref:`specifying a file descriptor <path_fd>`.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionadded:: 3.3
 
@@ -2962,7 +2953,7 @@
           for name in dirs:
               os.rmdir(name, dir_fd=rootfd)
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -3139,7 +3130,7 @@
    you can check whether or not it is available using :data:`os.supports_fd`.
    If it is unavailable, using it will raise a :exc:`NotImplementedError`.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionadded:: 3.3
       Added support for specifying an open file descriptor for *path*
@@ -3173,7 +3164,7 @@
 
    Exit code that means no error occurred.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_USAGE
@@ -3181,49 +3172,49 @@
    Exit code that means the command was used incorrectly, such as when the wrong
    number of arguments are given.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_DATAERR
 
    Exit code that means the input data was incorrect.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_NOINPUT
 
    Exit code that means an input file did not exist or was not readable.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_NOUSER
 
    Exit code that means a specified user did not exist.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_NOHOST
 
    Exit code that means a specified host did not exist.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_UNAVAILABLE
 
    Exit code that means that a required service is unavailable.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_SOFTWARE
 
    Exit code that means an internal software error was detected.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_OSERR
@@ -3231,7 +3222,7 @@
    Exit code that means an operating system error was detected, such as the
    inability to fork or create a pipe.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_OSFILE
@@ -3239,21 +3230,21 @@
    Exit code that means some system file did not exist, could not be opened, or had
    some other kind of error.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_CANTCREAT
 
    Exit code that means a user specified output file could not be created.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_IOERR
 
    Exit code that means that an error occurred while doing I/O on some file.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_TEMPFAIL
@@ -3262,7 +3253,7 @@
    that may not really be an error, such as a network connection that couldn't be
    made during a retryable operation.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_PROTOCOL
@@ -3270,7 +3261,7 @@
    Exit code that means that a protocol exchange was illegal, invalid, or not
    understood.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_NOPERM
@@ -3278,21 +3269,21 @@
    Exit code that means that there were insufficient permissions to perform the
    operation (but not intended for file system problems).
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_CONFIG
 
    Exit code that means that some kind of configuration error occurred.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: EX_NOTFOUND
 
    Exit code that means something like "an entry was not found".
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: fork()
@@ -3307,7 +3298,7 @@
 
       See :mod:`ssl` for applications that use the SSL module with fork().
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: forkpty()
@@ -3318,7 +3309,7 @@
    master end of the pseudo-terminal.  For a more portable approach, use the
    :mod:`pty` module.  If an error occurs :exc:`OSError` is raised.
 
-   Availability: some flavors of Unix.
+   .. availability:: some flavors of Unix.
 
 
 .. function:: kill(pid, sig)
@@ -3352,14 +3343,14 @@
 
    Send the signal *sig* to the process group *pgid*.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: nice(increment)
 
    Add *increment* to the process's "niceness".  Return the new niceness.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: plock(op)
@@ -3367,7 +3358,7 @@
    Lock program segments into memory.  The value of *op* (defined in
    ``<sys/lock.h>``) determines which segments are locked.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: popen(cmd, mode='r', buffering=-1)
@@ -3496,7 +3487,7 @@
 
    There is no way to unregister a function.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.7
 
@@ -3560,10 +3551,10 @@
       L = ['cp', 'index.html', '/dev/null']
       os.spawnvpe(os.P_WAIT, 'cp', L, os.environ)
 
-   Availability: Unix, Windows.  :func:`spawnlp`, :func:`spawnlpe`, :func:`spawnvp`
-   and :func:`spawnvpe` are not available on Windows.  :func:`spawnle` and
-   :func:`spawnve` are not thread-safe on Windows; we advise you to use the
-   :mod:`subprocess` module instead.
+   .. availability:: Unix, Windows.  :func:`spawnlp`, :func:`spawnlpe`, :func:`spawnvp`
+      and :func:`spawnvpe` are not available on Windows.  :func:`spawnle` and
+      :func:`spawnve` are not thread-safe on Windows; we advise you to use the
+      :mod:`subprocess` module instead.
 
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.
@@ -3577,7 +3568,7 @@
    will return as soon as the new process has been created, with the process id as
    the return value.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
 
 .. data:: P_WAIT
@@ -3588,7 +3579,7 @@
    of the process the run is successful, or ``-signal`` if a signal kills the
    process.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
 
 .. data:: P_DETACH
@@ -3600,7 +3591,7 @@
    console of the calling process. If :const:`P_OVERLAY` is used, the current
    process will be replaced; the :func:`spawn\* <spawnl>` function will not return.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
 
 .. function:: startfile(path[, operation])
@@ -3629,7 +3620,7 @@
    function is not resolved until this function is first called.  If the function
    cannot be resolved, :exc:`NotImplementedError` will be raised.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
 
 .. function:: system(command)
@@ -3656,7 +3647,7 @@
    to using this function.  See the :ref:`subprocess-replacements` section in
    the :mod:`subprocess` documentation for some helpful recipes.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
 
 .. function:: times()
@@ -3679,7 +3670,7 @@
    On Windows, only :attr:`user` and :attr:`system` are known; the other
    attributes are zero.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
    .. versionchanged:: 3.3
       Return type changed from a tuple to a tuple-like object
@@ -3694,7 +3685,7 @@
    number is zero); the high bit of the low byte is set if a core file was
    produced.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 .. function:: waitid(idtype, id, options)
 
@@ -3709,7 +3700,7 @@
    :attr:`si_code` or ``None`` if :data:`WNOHANG` is specified and there are no
    children in a waitable state.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -3720,7 +3711,7 @@
    These are the possible values for *idtype* in :func:`waitid`. They affect
    how *id* is interpreted.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -3731,7 +3722,7 @@
    Flags that can be used in *options* in :func:`waitid` that specify what
    child signal to wait for.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -3744,7 +3735,7 @@
    These are the possible values for :attr:`si_code` in the result returned by
    :func:`waitid`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -3791,7 +3782,7 @@
    option argument is the same as that provided to :func:`waitpid` and
    :func:`wait4`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: wait4(pid, options)
@@ -3802,7 +3793,7 @@
    resource usage information.  The arguments to :func:`wait4` are the same
    as those provided to :func:`waitpid`.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: WNOHANG
@@ -3810,7 +3801,7 @@
    The option for :func:`waitpid` to return immediately if no child process status
    is available immediately. The function returns ``(0, 0)`` in this case.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: WCONTINUED
@@ -3818,7 +3809,7 @@
    This option causes child processes to be reported if they have been continued
    from a job control stop since their status was last reported.
 
-   Availability: some Unix systems.
+   .. availability:: some Unix systems.
 
 
 .. data:: WUNTRACED
@@ -3826,7 +3817,7 @@
    This option causes child processes to be reported if they have been stopped but
    their current state has not been reported since they were stopped.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 The following functions take a process status code as returned by
@@ -3838,7 +3829,7 @@
    Return ``True`` if a core dump was generated for the process, otherwise
    return ``False``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: WIFCONTINUED(status)
@@ -3846,7 +3837,7 @@
    Return ``True`` if the process has been continued from a job control stop,
    otherwise return ``False``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: WIFSTOPPED(status)
@@ -3854,7 +3845,7 @@
    Return ``True`` if the process has been stopped, otherwise return
    ``False``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: WIFSIGNALED(status)
@@ -3862,7 +3853,7 @@
    Return ``True`` if the process exited due to a signal, otherwise return
    ``False``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: WIFEXITED(status)
@@ -3870,7 +3861,7 @@
    Return ``True`` if the process exited using the :manpage:`exit(2)` system call,
    otherwise return ``False``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: WEXITSTATUS(status)
@@ -3878,21 +3869,21 @@
    If ``WIFEXITED(status)`` is true, return the integer parameter to the
    :manpage:`exit(2)` system call.  Otherwise, the return value is meaningless.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: WSTOPSIG(status)
 
    Return the signal which caused the process to stop.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: WTERMSIG(status)
 
    Return the signal which caused the process to exit.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 Interface to the scheduler
@@ -4038,7 +4029,7 @@
    included in ``confstr_names``, an :exc:`OSError` is raised with
    :const:`errno.EINVAL` for the error number.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: confstr_names
@@ -4047,7 +4038,7 @@
    defined for those names by the host operating system. This can be used to
    determine the set of names known to the system.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: cpu_count()
@@ -4068,7 +4059,7 @@
    1, 5, and 15 minutes or raises :exc:`OSError` if the load average was
    unobtainable.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. function:: sysconf(name)
@@ -4078,7 +4069,7 @@
    the *name* parameter for :func:`confstr` apply here as well; the dictionary that
    provides information on the known names is given by ``sysconf_names``.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 
 .. data:: sysconf_names
@@ -4087,7 +4078,7 @@
    defined for those names by the host operating system. This can be used to
    determine the set of names known to the system.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 The following data values are used to support path manipulation operations.  These
 are defined for all platforms.
@@ -4199,7 +4190,7 @@
    See also the `Linux getrandom() manual page
    <http://man7.org/linux/man-pages/man2/getrandom.2.html>`_.
 
-   Availability: Linux 3.17 and newer.
+   .. availability:: Linux 3.17 and newer.
 
    .. versionadded:: 3.6
 
diff --git a/Doc/library/resource.rst b/Doc/library/resource.rst
index bdfe5f6..bd49c87 100644
--- a/Doc/library/resource.rst
+++ b/Doc/library/resource.rst
@@ -92,7 +92,7 @@
    :exc:`PermissionError` when the user doesn't have ``CAP_SYS_RESOURCE`` for
    the process.
 
-   Availability: Linux 2.6.36 or later with glibc 2.13 or later
+   .. availability:: Linux 2.6.36 or later with glibc 2.13 or later.
 
    .. versionadded:: 3.4
 
@@ -178,7 +178,7 @@
 
    The number of bytes that can be allocated for POSIX message queues.
 
-   Availability: Linux 2.6.8 or later.
+   .. availability:: Linux 2.6.8 or later.
 
    .. versionadded:: 3.4
 
@@ -187,7 +187,7 @@
 
    The ceiling for the process's nice level (calculated as 20 - rlim_cur).
 
-   Availability: Linux 2.6.12 or later.
+   .. availability:: Linux 2.6.12 or later.
 
    .. versionadded:: 3.4
 
@@ -196,7 +196,7 @@
 
    The ceiling of the real-time priority.
 
-   Availability: Linux 2.6.12 or later.
+   .. availability:: Linux 2.6.12 or later.
 
    .. versionadded:: 3.4
 
@@ -206,7 +206,7 @@
    The time limit (in microseconds) on CPU time that a process can spend
    under real-time scheduling without making a blocking syscall.
 
-   Availability: Linux 2.6.25 or later.
+   .. availability:: Linux 2.6.25 or later.
 
    .. versionadded:: 3.4
 
@@ -215,7 +215,7 @@
 
    The number of signals which the process may queue.
 
-   Availability: Linux 2.6.8 or later.
+   .. availability:: Linux 2.6.8 or later.
 
    .. versionadded:: 3.4
 
@@ -225,7 +225,7 @@
    This limits the amount of network memory, and hence the amount of mbufs,
    that this user may hold at any time.
 
-   Availability: FreeBSD 9 or later.
+   .. availability:: FreeBSD 9 or later.
 
    .. versionadded:: 3.4
 
@@ -236,7 +236,7 @@
    This limit is enforced only if bit 1 of the vm.overcommit sysctl is set.
    Please see :manpage:`tuning(7)` for a complete description of this sysctl.
 
-   Availability: FreeBSD 9 or later.
+   .. availability:: FreeBSD 9 or later.
 
    .. versionadded:: 3.4
 
@@ -244,7 +244,7 @@
 
    The maximum number of pseudo-terminals created by this user id.
 
-   Availability: FreeBSD 9 or later.
+   .. availability:: FreeBSD 9 or later.
 
    .. versionadded:: 3.4
 
diff --git a/Doc/library/select.rst b/Doc/library/select.rst
index 8feedaa..f5b25db 100644
--- a/Doc/library/select.rst
+++ b/Doc/library/select.rst
@@ -171,7 +171,9 @@
    :func:`poll` or another interface in this module.  This doesn't apply
    to other kind of file-like objects such as sockets.
 
-   This value is guaranteed by POSIX to be at least 512.  Availability: Unix.
+   This value is guaranteed by POSIX to be at least 512.
+
+   .. availability:: Unix
 
    .. versionadded:: 3.2
 
diff --git a/Doc/library/shutil.rst b/Doc/library/shutil.rst
index d882627..6b4ce14 100644
--- a/Doc/library/shutil.rst
+++ b/Doc/library/shutil.rst
@@ -351,7 +351,7 @@
    .. versionchanged:: 3.8
      On Windows, *path* can now be a file or directory.
 
-   Availability: Unix, Windows.
+   .. availability:: Unix, Windows.
 
 .. function:: chown(path, user=None, group=None)
 
@@ -362,7 +362,7 @@
 
    See also :func:`os.chown`, the underlying function.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
diff --git a/Doc/library/signal.rst b/Doc/library/signal.rst
index bf07559..5c48c88 100644
--- a/Doc/library/signal.rst
+++ b/Doc/library/signal.rst
@@ -106,7 +106,7 @@
    The signal corresponding to the :kbd:`Ctrl+C` keystroke event. This signal can
    only be used with :func:`os.kill`.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
    .. versionadded:: 3.2
 
@@ -116,7 +116,7 @@
    The signal corresponding to the :kbd:`Ctrl+Break` keystroke event. This signal can
    only be used with :func:`os.kill`.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
    .. versionadded:: 3.2
 
@@ -193,7 +193,9 @@
    then the number of seconds before any previously set alarm was to have been
    delivered. If *time* is zero, no alarm is scheduled, and any scheduled alarm is
    canceled.  If the return value is zero, no alarm is currently scheduled.  (See
-   the Unix man page :manpage:`alarm(2)`.) Availability: Unix.
+   the Unix man page :manpage:`alarm(2)`.)
+
+   .. availability:: Unix.
 
 
 .. function:: getsignal(signalnum)
@@ -252,8 +254,8 @@
    If *signalnum* is 0, then no signal is sent, but error checking is still
    performed; this can be used to check if the target thread is still running.
 
-   Availability: Unix (see the man page :manpage:`pthread_kill(3)` for further
-   information).
+   .. availability:: Unix (see the man page :manpage:`pthread_kill(3)` for further
+      information).
 
    See also :func:`os.kill`.
 
@@ -283,8 +285,8 @@
    For example, ``signal.pthread_sigmask(signal.SIG_BLOCK, [])`` reads the
    signal mask of the calling thread.
 
-   Availability: Unix. See the man page :manpage:`sigprocmask(3)` and
-   :manpage:`pthread_sigmask(3)` for further information.
+   .. availability:: Unix. See the man page :manpage:`sigprocmask(3)` and
+      :manpage:`pthread_sigmask(3)` for further information.
 
    See also :func:`pause`, :func:`sigpending` and :func:`sigwait`.
 
@@ -309,13 +311,16 @@
    The old values are returned as a tuple: (delay, interval).
 
    Attempting to pass an invalid interval timer will cause an
-   :exc:`ItimerError`.  Availability: Unix.
+   :exc:`ItimerError`.
+
+   .. availability:: Unix.
 
 
 .. function:: getitimer(which)
 
    Returns current value of a given interval timer specified by *which*.
-   Availability: Unix.
+
+   .. availability:: Unix.
 
 
 .. function:: set_wakeup_fd(fd, *, warn_on_full_buffer=True)
@@ -365,8 +370,10 @@
 
    Change system call restart behaviour: if *flag* is :const:`False`, system
    calls will be restarted when interrupted by signal *signalnum*, otherwise
-   system calls will be interrupted.  Returns nothing.  Availability: Unix (see
-   the man page :manpage:`siginterrupt(3)` for further information).
+   system calls will be interrupted.  Returns nothing.
+
+   .. availability:: Unix (see the man page :manpage:`siginterrupt(3)`
+      for further information).
 
    Note that installing a signal handler with :func:`signal` will reset the
    restart behaviour to interruptible by implicitly calling
@@ -405,8 +412,8 @@
    thread (i.e., the signals which have been raised while blocked).  Return the
    set of the pending signals.
 
-   Availability: Unix (see the man page :manpage:`sigpending(2)` for further
-   information).
+   .. availability:: Unix (see the man page :manpage:`sigpending(2)` for further
+      information).
 
    See also :func:`pause`, :func:`pthread_sigmask` and :func:`sigwait`.
 
@@ -419,8 +426,8 @@
    signals specified in the signal set *sigset*.  The function accepts the signal
    (removes it from the pending list of signals), and returns the signal number.
 
-   Availability: Unix (see the man page :manpage:`sigwait(3)` for further
-   information).
+   .. availability:: Unix (see the man page :manpage:`sigwait(3)` for further
+      information).
 
    See also :func:`pause`, :func:`pthread_sigmask`, :func:`sigpending`,
    :func:`sigwaitinfo` and :func:`sigtimedwait`.
@@ -444,8 +451,8 @@
    :attr:`si_errno`, :attr:`si_pid`, :attr:`si_uid`, :attr:`si_status`,
    :attr:`si_band`.
 
-   Availability: Unix (see the man page :manpage:`sigwaitinfo(2)` for further
-   information).
+   .. availability:: Unix (see the man page :manpage:`sigwaitinfo(2)` for further
+      information).
 
    See also :func:`pause`, :func:`sigwait` and :func:`sigtimedwait`.
 
@@ -463,8 +470,8 @@
    specifying a timeout. If *timeout* is specified as :const:`0`, a poll is
    performed. Returns :const:`None` if a timeout occurs.
 
-   Availability: Unix (see the man page :manpage:`sigtimedwait(2)` for further
-   information).
+   .. availability:: Unix (see the man page :manpage:`sigtimedwait(2)` for further
+      information).
 
    See also :func:`pause`, :func:`sigwait` and :func:`sigwaitinfo`.
 
diff --git a/Doc/library/socket.rst b/Doc/library/socket.rst
index bfb315f..d466884 100644
--- a/Doc/library/socket.rst
+++ b/Doc/library/socket.rst
@@ -161,7 +161,7 @@
 
   - *feat* and *mask* are unsigned 32bit integers.
 
-  Availability Linux 2.6.38, some algorithm types require more recent Kernels.
+  .. availability:: Linux 2.6.38, some algorithm types require more recent Kernels.
 
   .. versionadded:: 3.6
 
@@ -169,7 +169,7 @@
   their hosts. The sockets are represented as a ``(CID, port)`` tuple
   where the context ID or CID and port are integers.
 
-  Availability: Linux >= 4.8 QEMU >= 2.8 ESX >= 4.0 ESX Workstation >= 6.5
+  .. availability:: Linux >= 4.8 QEMU >= 2.8 ESX >= 4.0 ESX Workstation >= 6.5.
 
   .. versionadded:: 3.7
 
@@ -313,7 +313,7 @@
       `Secure File Descriptor Handling <http://udrepper.livejournal.com/20407.html>`_
       for a more thorough explanation.
 
-   Availability: Linux >= 2.6.27.
+   .. availability:: Linux >= 2.6.27.
 
    .. versionadded:: 3.2
 
@@ -361,7 +361,7 @@
    Many constants of these forms, documented in the Linux documentation, are
    also defined in the socket module.
 
-   Availability: Linux >= 2.6.25.
+   .. availability:: Linux >= 2.6.25.
 
    .. versionadded:: 3.3
 
@@ -372,7 +372,7 @@
    Broadcast manager constants, documented in the Linux documentation, are also
    defined in the socket module.
 
-   Availability: Linux >= 2.6.25.
+   .. availability:: Linux >= 2.6.25.
 
    .. versionadded:: 3.4
 
@@ -384,7 +384,7 @@
 
    This constant is documented in the Linux documentation.
 
-   Availability: Linux >= 3.6.
+   .. availability:: Linux >= 3.6.
 
    .. versionadded:: 3.5
 
@@ -393,7 +393,7 @@
    CAN_ISOTP, in the CAN protocol family, is the ISO-TP (ISO 15765-2) protocol.
    ISO-TP constants, documented in the Linux documentation.
 
-   Availability: Linux >= 2.6.25
+   .. availability:: Linux >= 2.6.25.
 
    .. versionadded:: 3.7
 
@@ -405,7 +405,7 @@
    Many constants of these forms, documented in the Linux documentation, are
    also defined in the socket module.
 
-   Availability: Linux >= 2.2.
+   .. availability:: Linux >= 2.2.
 
 
 .. data:: AF_RDS
@@ -416,7 +416,7 @@
    Many constants of these forms, documented in the Linux documentation, are
    also defined in the socket module.
 
-   Availability: Linux >= 2.6.30.
+   .. availability:: Linux >= 2.6.30.
 
    .. versionadded:: 3.3
 
@@ -444,7 +444,7 @@
 
    Constants for Linux Kernel cryptography.
 
-   Availability: Linux >= 2.6.38.
+   .. availability:: Linux >= 2.6.38.
 
    .. versionadded:: 3.6
 
@@ -456,13 +456,13 @@
 
    Constants for Linux host/guest communication.
 
-   Availability: Linux >= 4.8.
+   .. availability:: Linux >= 4.8.
 
    .. versionadded:: 3.7
 
 .. data:: AF_LINK
 
-  Availability: BSD, OSX.
+  .. availability:: BSD, OSX.
 
   .. versionadded:: 3.4
 
@@ -493,7 +493,7 @@
    Constant for Qualcomm's IPC router protocol, used to communicate with
    service providing remote processors.
 
-   Availability: Linux >= 4.7.
+   .. availability:: Linux >= 4.7.
 
 Functions
 ^^^^^^^^^
@@ -618,7 +618,7 @@
    Instantiate a socket from data obtained from the :meth:`socket.share`
    method.  The socket is assumed to be in blocking mode.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
    .. versionadded:: 3.3
 
@@ -865,7 +865,7 @@
    both the value of *address_family* and the underlying implementation of
    :c:func:`inet_pton`.
 
-   Availability: Unix (maybe not all platforms), Windows.
+   .. availability:: Unix (maybe not all platforms), Windows.
 
    .. versionchanged:: 3.4
       Windows support added
@@ -885,7 +885,7 @@
    length for the specified address family, :exc:`ValueError` will be raised.
    :exc:`OSError` is raised for errors from the call to :func:`inet_ntop`.
 
-   Availability: Unix (maybe not all platforms), Windows.
+   .. availability:: Unix (maybe not all platforms), Windows.
 
    .. versionchanged:: 3.4
       Windows support added
@@ -911,7 +911,7 @@
    buffer.  Raises :exc:`OverflowError` if *length* is outside the
    permissible range of values.
 
-   Availability: most Unix platforms, possibly others.
+   .. availability:: most Unix platforms, possibly others.
 
    .. versionadded:: 3.3
 
@@ -932,7 +932,7 @@
    amount of ancillary data that can be received, since additional
    data may be able to fit into the padding area.
 
-   Availability: most Unix platforms, possibly others.
+   .. availability:: most Unix platforms, possibly others.
 
    .. versionadded:: 3.3
 
@@ -957,7 +957,7 @@
    Set the machine's hostname to *name*.  This will raise an
    :exc:`OSError` if you don't have enough rights.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -968,7 +968,7 @@
    (index int, name string) tuples.
    :exc:`OSError` if the system call fails.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -979,7 +979,7 @@
    interface name.
    :exc:`OSError` if no interface with the given name exists.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -990,7 +990,7 @@
    interface index number.
    :exc:`OSError` if no interface with the given index exists.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -1317,7 +1317,7 @@
                   fds.fromstring(cmsg_data[:len(cmsg_data) - (len(cmsg_data) % fds.itemsize)])
           return msg, list(fds)
 
-   Availability: most Unix platforms, possibly others.
+   .. availability:: most Unix platforms, possibly others.
 
    .. versionadded:: 3.3
 
@@ -1359,7 +1359,7 @@
       >>> [b1, b2, b3]
       [bytearray(b'Mary'), bytearray(b'01 had a 9'), bytearray(b'little lamb---')]
 
-   Availability: most Unix platforms, possibly others.
+   .. availability:: most Unix platforms, possibly others.
 
    .. versionadded:: 3.3
 
@@ -1463,7 +1463,7 @@
       def send_fds(sock, msg, fds):
           return sock.sendmsg([msg], [(socket.SOL_SOCKET, socket.SCM_RIGHTS, array.array("i", fds))])
 
-   Availability: most Unix platforms, possibly others.
+   .. availability:: most Unix platforms, possibly others.
 
    .. versionadded:: 3.3
 
@@ -1477,7 +1477,7 @@
    Specialized version of :meth:`~socket.sendmsg` for :const:`AF_ALG` socket.
    Set mode, IV, AEAD associated data length and flags for :const:`AF_ALG` socket.
 
-   Availability: Linux >= 2.6.38
+   .. availability:: Linux >= 2.6.38.
 
    .. versionadded:: 3.6
 
@@ -1578,7 +1578,7 @@
    Once this method has been called, it is safe to close the socket since
    the operating system has already duplicated it for the target process.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
    .. versionadded:: 3.3
 
diff --git a/Doc/library/ssl.rst b/Doc/library/ssl.rst
index 9dadc58..5b0ef2e 100644
--- a/Doc/library/ssl.rst
+++ b/Doc/library/ssl.rst
@@ -328,7 +328,7 @@
    See http://egd.sourceforge.net/ or http://prngd.sourceforge.net/ for sources
    of entropy-gathering daemons.
 
-   Availability: not available with LibreSSL and OpenSSL > 1.1.0
+   .. availability:: not available with LibreSSL and OpenSSL > 1.1.0.
 
 .. function:: RAND_add(bytes, entropy)
 
@@ -460,8 +460,8 @@
    * :attr:`openssl_capath_env` - OpenSSL's environment key that points to a capath,
    * :attr:`openssl_capath` - hard coded path to a capath directory
 
-   Availability: LibreSSL ignores the environment vars
-   :attr:`openssl_cafile_env` and :attr:`openssl_capath_env`
+   .. availability:: LibreSSL ignores the environment vars
+     :attr:`openssl_cafile_env` and :attr:`openssl_capath_env`.
 
    .. versionadded:: 3.4
 
@@ -484,7 +484,7 @@
       [(b'data...', 'x509_asn', {'1.3.6.1.5.5.7.3.1', '1.3.6.1.5.5.7.3.2'}),
        (b'data...', 'x509_asn', True)]
 
-   Availability: Windows.
+   .. availability:: Windows.
 
    .. versionadded:: 3.4
 
@@ -499,7 +499,7 @@
    :const:`x509_asn` for X.509 ASN.1 data or :const:`pkcs_7_asn` for
    PKCS#7 ASN.1 data.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
    .. versionadded:: 3.4
 
@@ -1610,7 +1610,7 @@
          'strength_bits': 128,
          'symmetric': 'aes-128-gcm'}]
 
-   Availability: OpenSSL 1.0.2+
+   .. availability:: OpenSSL 1.0.2+.
 
    .. versionadded:: 3.6
 
diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst
index aa889ed..8f4377b 100644
--- a/Doc/library/subprocess.rst
+++ b/Doc/library/subprocess.rst
@@ -1330,7 +1330,7 @@
       >>> subprocess.getstatusoutput('/bin/kill $$')
       (-15, '')
 
-   Availability: POSIX & Windows
+   .. availability:: POSIX & Windows.
 
    .. versionchanged:: 3.3.4
       Windows support was added.
@@ -1350,7 +1350,7 @@
       >>> subprocess.getoutput('ls /bin/ls')
       '/bin/ls'
 
-   Availability: POSIX & Windows
+   .. availability:: POSIX & Windows.
 
    .. versionchanged:: 3.3.4
       Windows support added
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index cd43e54..46d8db0 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -161,7 +161,9 @@
 
 .. data:: dllhandle
 
-   Integer specifying the handle of the Python DLL. Availability: Windows.
+   Integer specifying the handle of the Python DLL.
+
+   .. availability:: Windows.
 
 
 .. function:: displayhook(value)
@@ -477,7 +479,7 @@
 
    Return the build time API version of Android as an integer.
 
-   Availability: Android.
+   .. availability:: Android.
 
    .. versionadded:: 3.7
 
@@ -501,7 +503,9 @@
    Return the current value of the flags that are used for
    :c:func:`dlopen` calls.  Symbolic names for the flag values can be
    found in the :mod:`os` module (``RTLD_xxx`` constants, e.g.
-   :data:`os.RTLD_LAZY`).  Availability: Unix.
+   :data:`os.RTLD_LAZY`).
+
+   .. availability:: Unix.
 
 
 .. function:: getfilesystemencoding()
@@ -669,7 +673,7 @@
    is being emulated for the process. It is intended for use in logging rather
    than for feature detection.
 
-   Availability: Windows.
+   .. availability:: Windows.
 
    .. versionchanged:: 3.2
       Changed to a named tuple and added *service_pack_minor*,
@@ -1094,7 +1098,7 @@
    can be found in the :mod:`os` module (``RTLD_xxx`` constants, e.g.
    :data:`os.RTLD_LAZY`).
 
-   Availability: Unix.
+   .. availability:: Unix.
 
 .. function:: setprofile(profilefunc)
 
@@ -1340,7 +1344,7 @@
    This is equivalent to defining the :envvar:`PYTHONLEGACYWINDOWSFSENCODING`
    environment variable before launching Python.
 
-   Availability: Windows
+   .. availability:: Windows.
 
    .. versionadded:: 3.6
       See :pep:`529` for more details.
@@ -1486,7 +1490,9 @@
    stored as string resource 1000 in the Python DLL.  The value is normally the
    first three characters of :const:`version`.  It is provided in the :mod:`sys`
    module for informational purposes; modifying this value has no effect on the
-   registry keys used by Python. Availability: Windows.
+   registry keys used by Python.
+
+   .. availability:: Windows.
 
 
 .. data:: _xoptions
diff --git a/Doc/library/threading.rst b/Doc/library/threading.rst
index e6185c5..a9d5268 100644
--- a/Doc/library/threading.rst
+++ b/Doc/library/threading.rst
@@ -100,7 +100,8 @@
    memory page size - platform documentation should be referred to for more
    information (4 KiB pages are common; using multiples of 4096 for the stack size is
    the suggested approach in the absence of more specific information).
-   Availability: Windows, systems with POSIX threads.
+
+   .. availability:: Windows, systems with POSIX threads.
 
 
 This module also defines the following constant:
diff --git a/Doc/library/time.rst b/Doc/library/time.rst
index 3eddc3f..56f972c 100644
--- a/Doc/library/time.rst
+++ b/Doc/library/time.rst
@@ -170,8 +170,8 @@
       Passing an invalid or expired *thread_id* may result in
       undefined behavior, such as segmentation fault.
 
-   Availability: Unix (see the man page for :manpage:`pthread_getcpuclockid(3)` for
-   further information)
+   .. availability:: Unix (see the man page for :manpage:`pthread_getcpuclockid(3)` for
+      further information).
 
    .. versionadded:: 3.7
 
@@ -180,7 +180,7 @@
    Return the resolution (precision) of the specified clock *clk_id*.  Refer to
    :ref:`time-clock-id-constants` for a list of accepted values for *clk_id*.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -190,7 +190,7 @@
    Return the time of the specified clock *clk_id*.  Refer to
    :ref:`time-clock-id-constants` for a list of accepted values for *clk_id*.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -199,7 +199,7 @@
 
    Similar to :func:`clock_gettime` but return time as nanoseconds.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.7
 
@@ -209,7 +209,7 @@
    Set the time of the specified clock *clk_id*.  Currently,
    :data:`CLOCK_REALTIME` is the only accepted value for *clk_id*.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -218,7 +218,7 @@
 
    Similar to :func:`clock_settime` but set time with nanoseconds.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.7
 
@@ -617,8 +617,8 @@
    returned value is undefined, so that only the difference between the results
    of consecutive calls in the same thread is valid.
 
-   Availability:  Windows, Linux, Unix systems supporting
-   ``CLOCK_THREAD_CPUTIME_ID``.
+   .. availability::  Windows, Linux, Unix systems supporting
+      ``CLOCK_THREAD_CPUTIME_ID``.
 
    .. versionadded:: 3.7
 
@@ -647,7 +647,7 @@
    nonzero if there is a time, past, present or future when daylight saving time
    applies).
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. note::
 
@@ -743,7 +743,7 @@
    have  discontinuities if the time is changed using ``settimeofday()`` or
    similar.
 
-   Availability: Linux 2.6.39 or later.
+   .. availability:: Linux 2.6.39 or later.
 
    .. versionadded:: 3.7
 
@@ -754,7 +754,7 @@
    hardware source, and may give close to nanosecond resolution.
    ``CLOCK_HIGHRES`` is the nonadjustable, high-resolution clock.
 
-   Availability: Solaris.
+   .. availability:: Solaris.
 
    .. versionadded:: 3.3
 
@@ -764,7 +764,7 @@
    Clock that cannot be set and represents monotonic time since some unspecified
    starting point.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -783,7 +783,7 @@
 
    High-resolution per-process timer from the CPU.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
@@ -792,7 +792,7 @@
 
    High-resolution per-process timer from the CPU.
 
-   Availability: FreeBSD, NetBSD 7 or later, OpenBSD.
+   .. availability:: FreeBSD, NetBSD 7 or later, OpenBSD.
 
    .. versionadded:: 3.7
 
@@ -812,7 +812,7 @@
    suspended, providing accurate uptime measurement, both absolute and
    interval.
 
-   Availability: FreeBSD, OpenBSD 5.5 or later.
+   .. availability:: FreeBSD, OpenBSD 5.5 or later.
 
    .. versionadded:: 3.7
 
@@ -825,7 +825,7 @@
    System-wide real-time clock.  Setting this clock requires appropriate
    privileges.
 
-   Availability: Unix.
+   .. availability:: Unix.
 
    .. versionadded:: 3.3
 
diff --git a/Doc/tools/extensions/pyspecific.py b/Doc/tools/extensions/pyspecific.py
index 8036daa..132920f 100644
--- a/Doc/tools/extensions/pyspecific.py
+++ b/Doc/tools/extensions/pyspecific.py
@@ -131,6 +131,25 @@
         return [pnode]
 
 
+# Support for documenting platform availability
+
+class Availability(Directive):
+
+    has_content = False
+    required_arguments = 1
+    optional_arguments = 0
+    final_argument_whitespace = True
+
+    def run(self):
+        pnode = nodes.paragraph(classes=['availability'])
+        n, m = self.state.inline_text(':ref:`Availability <availability>`: ',
+                                      self.lineno)
+        pnode.extend(n + m)
+        n, m = self.state.inline_text(self.arguments[0], self.lineno)
+        pnode.extend(n + m)
+        return [pnode]
+
+
 # Support for documenting decorators
 
 class PyDecoratorMixin(object):
@@ -401,6 +420,7 @@
     app.add_role('issue', issue_role)
     app.add_role('source', source_role)
     app.add_directive('impl-detail', ImplementationDetail)
+    app.add_directive('availability', Availability)
     app.add_directive('deprecated-removed', DeprecatedRemoved)
     app.add_builder(PydocTopicsBuilder)
     app.add_builder(suspicious.CheckSuspiciousMarkupBuilder)
diff --git a/Doc/tools/rstlint.py b/Doc/tools/rstlint.py
index 2c1816e..a3024d6 100755
--- a/Doc/tools/rstlint.py
+++ b/Doc/tools/rstlint.py
@@ -27,17 +27,18 @@
     'table', 'target-notes', 'tip', 'title', 'topic', 'unicode', 'warning',
     # Sphinx and Python docs custom ones
     'acks', 'attribute', 'autoattribute', 'autoclass', 'autodata',
-    'autoexception', 'autofunction', 'automethod', 'automodule', 'centered',
-    'cfunction', 'class', 'classmethod', 'cmacro', 'cmdoption', 'cmember',
-    'code-block', 'confval', 'cssclass', 'ctype', 'currentmodule', 'cvar',
-    'data', 'decorator', 'decoratormethod', 'deprecated-removed',
-    'deprecated(?!-removed)', 'describe', 'directive', 'doctest', 'envvar',
-    'event', 'exception', 'function', 'glossary', 'highlight', 'highlightlang',
-    'impl-detail', 'index', 'literalinclude', 'method', 'miscnews', 'module',
-    'moduleauthor', 'opcode', 'pdbcommand', 'productionlist',
-    'program', 'role', 'sectionauthor', 'seealso', 'sourcecode', 'staticmethod',
-    'tabularcolumns', 'testcode', 'testoutput', 'testsetup', 'toctree', 'todo',
-    'todolist', 'versionadded', 'versionchanged'
+    'autoexception', 'autofunction', 'automethod', 'automodule',
+    'availability', 'centered', 'cfunction', 'class', 'classmethod', 'cmacro',
+    'cmdoption', 'cmember', 'code-block', 'confval', 'cssclass', 'ctype',
+    'currentmodule', 'cvar', 'data', 'decorator', 'decoratormethod',
+    'deprecated-removed', 'deprecated(?!-removed)', 'describe', 'directive',
+    'doctest', 'envvar', 'event', 'exception', 'function', 'glossary',
+    'highlight', 'highlightlang', 'impl-detail', 'index', 'literalinclude',
+    'method', 'miscnews', 'module', 'moduleauthor', 'opcode', 'pdbcommand',
+    'productionlist', 'program', 'role', 'sectionauthor', 'seealso',
+    'sourcecode', 'staticmethod', 'tabularcolumns', 'testcode', 'testoutput',
+    'testsetup', 'toctree', 'todo', 'todolist', 'versionadded',
+    'versionchanged'
 ]
 
 all_directives = '(' + '|'.join(directives) + ')'
diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index b61df8a..bd3cdef 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -785,7 +785,7 @@
    This may also be enabled at runtime with
    :func:`sys._enablelegacywindowsfsencoding()`.
 
-   Availability: Windows
+   .. availability:: Windows.
 
    .. versionadded:: 3.6
       See :pep:`529` for more details.
@@ -799,7 +799,7 @@
    This variable is ignored if the standard streams are redirected (to files
    or pipes) rather than referring to console buffers.
 
-   Availability: Windows
+   .. availability:: Windows.
 
    .. versionadded:: 3.6
 
@@ -850,7 +850,7 @@
    order to force the interpreter to use ``ASCII`` instead of ``UTF-8`` for
    system interfaces.
 
-   Availability: \*nix
+   .. availability:: \*nix.
 
    .. versionadded:: 3.7
       See :pep:`538` for more details.
@@ -911,7 +911,7 @@
 
    Also available as the :option:`-X` ``utf8`` option.
 
-   Availability: \*nix
+   .. availability:: \*nix.
 
    .. versionadded:: 3.7
       See :pep:`540` for more details.
diff --git a/Misc/NEWS.d/next/Documentation/2018-10-03-20-39-25.bpo-11233.BX6Gen.rst b/Misc/NEWS.d/next/Documentation/2018-10-03-20-39-25.bpo-11233.BX6Gen.rst
new file mode 100644
index 0000000..0637dd6
--- /dev/null
+++ b/Misc/NEWS.d/next/Documentation/2018-10-03-20-39-25.bpo-11233.BX6Gen.rst
@@ -0,0 +1,2 @@
+Create availability directive for documentation.  Original patch by Georg
+Brandl.