The Plone ZopeProduct builds on the CMF to provide a very featureful and popular content management system.
It's filesystem directory name is CMFPlone.
Plone Documentation on Plone.org
Plone 2.0 API Documentation on ZDP (Created using epydoc )
Plone 2.0 UML Documentation on ZDP (Updated 2004/04/08)
Plone Quick Reference on ZDP (Updated 2004/04/08)