Some more notes about bytes/string filename APIs.
diff --git a/Doc/library/os.path.rst b/Doc/library/os.path.rst
index 71eeb53..795c9bc 100644
--- a/Doc/library/os.path.rst
+++ b/Doc/library/os.path.rst
@@ -19,6 +19,12 @@
names on Windows (in the standard ``mbcs`` encoding), hence Windows
applications should use string objects to access all files.
+.. note::
+
+ All of these functions accept either only bytes or only string objects as
+ their parameters. The result is an object of the same type, if a path or
+ file name is returned.
+
.. warning::
On Windows, many of these functions do not properly support UNC pathnames.