4Suite is a platform for XML processing and knowledge management, implemented in Python and C. It's split into three separate packages:

4Suite XML - XML, XPath, XSLT, related technologies and support libraries
4Suite RDF - RDF processing libraries and stand-alone DBMS
4Suite Repository - XML and RDF repository and server with a rules-based engine.

The core component, 4Suite XML, is a comprehensive Python library for XML processing. It is
implemented in Python and C and supports XML (SAX-like and DOM-like),
XPath, XSLT, RELAX NG, XUpdate, XInclude, XPointer, and more.