Specify which I/O ABC methods have implementations in the docs.
diff --git a/Doc/library/io.rst b/Doc/library/io.rst
index 62eaf6d..7cab685 100644
--- a/Doc/library/io.rst
+++ b/Doc/library/io.rst
@@ -189,6 +189,25 @@
Argument names are not part of the specification, and only the arguments of
:func:`open` are intended to be used as keyword arguments.
+The following table summarizes the ABCs provided by the :mod:`io` module:
+
+========================= ================== ======================== ==================================================
+ABC Inherits Stub Methods Mixin Methods and Properties
+========================= ================== ======================== ==================================================
+:class:`IOBase` ``fileno``, ``seek``, ``close``, ``closed``, ``__enter__``,
+ and ``truncate`` ``__exit__``, ``flush``, ``isatty``, ``__iter__``,
+ ``__next__``, ``readable``, ``readline``,
+ ``readlines``, ``seekable``, ``tell``,
+ ``writable``, and ``writelines``
+:class:`RawIOBase` :class:`IOBase` ``readinto`` and Inherited :class:`IOBase` methods, ``read``,
+ ``write`` and ``readall``
+:class:`BufferedIOBase` :class:`IOBase` ``detach``, ``read``, Inherited :class:`IOBase` methods, ``readinto``
+ ``read1``, and ``write``
+:class:`TextIOBase` :class:`IOBase` ``detach``, ``read``, Inherited :class:`IOBase` methods, ``encoding``,
+ ``readline``, and ``errors``, and ``newlines``
+ ``write``
+========================= ================== ======================== ==================================================
+
I/O Base Classes
^^^^^^^^^^^^^^^^