Issue #13557: Clarify effect of giving two different namespaces to exec or
execfile().
diff --git a/Doc/reference/simple_stmts.rst b/Doc/reference/simple_stmts.rst
index 05b78a0..ce22b67 100644
--- a/Doc/reference/simple_stmts.rst
+++ b/Doc/reference/simple_stmts.rst
@@ -993,6 +993,9 @@
it should be a dictionary, which will be used for both the global and the local
variables. If two expressions are given, they are used for the global and local
variables, respectively. If provided, *locals* can be any mapping object.
+Remember that at module level, globals and locals are the same dictionary. If
+two separate objects are given as *globals* and *locals*, the code will be
+executed as if it were embedded in a class definition.
.. versionchanged:: 2.4
Formerly, *locals* was required to be a dictionary.