--- rest25/library/constants.rst	2008-12-19 16:58:07.000000000 +0900
+++ rest262/library/constants.rst	2009-04-05 05:02:09.000000000 +0900
@@ -1,40 +1,73 @@
-
 Built-in Constants
 ==================
 
 A small number of constants live in the built-in namespace.  They are:
 
 
 .. data:: False
 
    The false value of the :class:`bool` type.
 
    .. versionadded:: 2.3
 
 
 .. data:: True
 
    The true value of the :class:`bool` type.
 
    .. versionadded:: 2.3
 
 
 .. data:: None
 
-   The sole value of ``types.NoneType``.  ``None`` is frequently used to represent
-   the absence of a value, as when default arguments are not passed to a function.
+   The sole value of :attr:`types.NoneType`.  ``None`` is frequently used to
+   represent the absence of a value, as when default arguments are not passed to a
+   function.
+
+   .. versionchanged:: 2.4
+      Assignments to ``None`` are illegal and raise a :exc:`SyntaxError`.
 
 
 .. data:: NotImplemented
 
    Special value which can be returned by the "rich comparison" special methods
    (:meth:`__eq__`, :meth:`__lt__`, and friends), to indicate that the comparison
    is not implemented with respect to the other type.
 
 
 .. data:: Ellipsis
 
    Special value used in conjunction with extended slicing syntax.
 
-   .. % XXX Someone who understands extended slicing should fill in here.
+   .. XXX Someone who understands extended slicing should fill in here.
+
+
+.. data:: __debug__
+
+   This constant is true if Python was not started with an :option:`-O` option.
+   Assignments to :const:`__debug__` are illegal and raise a :exc:`SyntaxError`.
+   See also the :keyword:`assert` statement.
+
+
+Constants added by the :mod:`site` module
+-----------------------------------------
+
+The :mod:`site` module (which is imported automatically during startup, except
+if the :option:`-S` command-line option is given) adds several constants to the
+built-in namespace.  They are useful for the interactive interpreter shell and
+should not be used in programs.
+
+.. data:: quit([code=None])
+          exit([code=None])
+
+   Objects that when printed, print a message like "Use quit() or Ctrl-D
+   (i.e. EOF) to exit", and when called, raise :exc:`SystemExit` with the
+   specified exit code, and when .
+
+.. data:: copyright
+          license
+          credits
 
+   Objects that when printed, print a message like "Type license() to see the
+   full license text", and when called, display the corresponding text in a
+   pager-like fashion (one screen at a time).
