Added the "provisional package" glossary term from PEP 411
diff --git a/Doc/glossary.rst b/Doc/glossary.rst
index 062918a..b44c5cc 100644
--- a/Doc/glossary.rst
+++ b/Doc/glossary.rst
@@ -523,6 +523,20 @@
definition), or pass several arguments as a list to a function. See
:term:`argument`.
+ provisional package
+ A provisional package is one which has been deliberately excluded from the
+ standard library's backwards compatibility guarantees. While major
+ changes to such packages are not expected, as long as they are marked
+ provisional, backwards incompatible changes (up to and including removal
+ of the package) may occur if deemed necessary by core developers. Such
+ changes will not be made gratuitously -- they will occur only if serious
+ flaws are uncovered that were missed prior to the inclusion of the
+ package.
+
+ This process allows the standard library to continue to evolve over time,
+ without locking in problematic design errors for extended periods of time.
+ See :pep:`411` for more details.
+
Python 3000
Nickname for the Python 3.x release line (coined long ago when the release
of version 3 was something in the distant future.) This is also