Where can I find the xml schema for http://linux.duke.edu/metadata/rpm?

I can use 'createrepo' to create primary.xml.gz etc and the
primary.xml includes the following header:
----
<?xml version="1.0" encoding="UTF-8" ?>
- <metadata xmlns="http://linux.duke.edu/metadata/common"
xmlns:rpm="http://linux.duke.edu/metadata/rpm" packages="2242">
----

My question is: Where can I find the xml schema for
http://linux.duke.edu/metadata/rpm and
http://linux.duke.edu/metadata/common?

Thanks!

Best Regards,
Xie, Bo