Issue #7631: Fix undefined references to the "built-in file object", which
has ceased to be.
diff --git a/Doc/library/filesys.rst b/Doc/library/filesys.rst
index b341f5f..31eaf0d 100644
--- a/Doc/library/filesys.rst
+++ b/Doc/library/filesys.rst
@@ -26,14 +26,13 @@
 
 .. seealso::
 
-   Section :ref:`bltin-file-objects`
-      A description of Python's built-in file objects.
-
    Module :mod:`os`
       Operating system interfaces, including functions to work with files at a lower
       level than the built-in file object.
 
    Module :mod:`io`
-      Python's framework for dealing with I/O including reading and writing
-      files.
+      Python's built-in I/O library, including both abstract classes and
+      some concrete classes such as file I/O.
 
+   Built-in function :func:`open`
+      The standard way to open files for reading and writing with Python.
diff --git a/Doc/library/socket.rst b/Doc/library/socket.rst
index ec8ff3d..0fee6d5 100644
--- a/Doc/library/socket.rst
+++ b/Doc/library/socket.rst
@@ -575,14 +575,16 @@
 
    .. index:: single: I/O control; buffering
 
-   Return a :dfn:`file object` associated with the socket.  (File objects are
-   described in :ref:`bltin-file-objects`.)  The file object references a
-   :cfunc:`dup`\ ped version of the socket file descriptor, so the file object
-   and socket object may be closed or garbage-collected independently.  The
-   socket must be in blocking mode (it can not have a timeout).  The optional
+   Return a :dfn:`file object` associated with the socket.  The exact
+   returned type depends on the arguments given to :meth:`makefile`.  These
    arguments are interpreted the same way as by the built-in :func:`open`
    function.
 
+   The returned file object references a :cfunc:`dup`\ ped version of the
+   socket file descriptor, so the file object and socket object may be
+   closed or garbage-collected independently.  The socket must be in
+   blocking mode (it can not have a timeout).
+
 
 .. method:: socket.recv(bufsize[, flags])
 
diff --git a/Doc/library/tokenize.rst b/Doc/library/tokenize.rst
index d66b07c..7017045 100644
--- a/Doc/library/tokenize.rst
+++ b/Doc/library/tokenize.rst
@@ -18,9 +18,8 @@
 
    The :func:`tokenize` generator requires one argument, *readline*, which
    must be a callable object which provides the same interface as the
-   :meth:`readline` method of built-in file objects (see section
-   :ref:`bltin-file-objects`).  Each call to the function should return one
-   line of input as bytes.
+   :meth:`io.IOBase.readline` method of file objects.  Each call to the
+   function should return one line of input as bytes.
 
    The generator produces 5-tuples with these members: the token type; the
    token string; a 2-tuple ``(srow, scol)`` of ints specifying the row and