Index: Doc/library/os.rst
===================================================================
--- Doc/library/os.rst	(revision 78324)
+++ Doc/library/os.rst	(working copy)
@@ -1280,6 +1280,15 @@
 
    .. index:: module: statvfs
 
+   Two module-level constants are defined for the :attr:`f_flag` attribute's
+   bit-flags: if :const:`ST_RDONLY` is set, the filesystem is mounted
+   read-only, and if :const:`ST_NOSUID` is set, the semantics of 
+   setuid/setgid bits are disabled or not supported.
+
+   .. versionchanged:: 2.7
+
+      The :const:`ST_RDONLY` and :const:`ST_NOSUID` were added.
+
    For backward compatibility, the return value is also accessible as a tuple whose
    values correspond to the attributes, in the order given above. The standard
    module :mod:`statvfs` defines constants that are useful for extracting