bpo-37751: Update `codecs.register()` doc. (GH-25643)
diff --git a/Doc/library/codecs.rst b/Doc/library/codecs.rst
index b15d293..0dcd88f 100644
--- a/Doc/library/codecs.rst
+++ b/Doc/library/codecs.rst
@@ -159,9 +159,13 @@
.. function:: register(search_function)
Register a codec search function. Search functions are expected to take one
- argument, being the encoding name in all lower case letters, and return a
- :class:`CodecInfo` object. In case a search function cannot find
- a given encoding, it should return ``None``.
+ argument, being the encoding name in all lower case letters with hyphens
+ and spaces converted to underscores, and return a :class:`CodecInfo` object.
+ In case a search function cannot find a given encoding, it should return
+ ``None``.
+
+ .. versionchanged:: 3.9
+ Hyphens and spaces are converted to underscore.
.. function:: unregister(search_function)