A quick reading of the patent and its claims, 6,505,212, shows that there is a substantial amoount of uncited prior art dating before the priority date (Feb 1998). The ignored literature includes SCCS, RCS, CVS, and a myrid of other products. A careful analysis of the patent in the light of the prior art would be needed to determine whether it was anticipated in the art and therefore, potentially invalid. Invalidating the patent would take litigation and deep pockets. On 25 Feb 2003, Marcin Kasperski wrote:

Does anyone know whether (and how) Zope itself and Zope users can have problems with the new Interwoven patent?

http://slashdot.org/article.pl?sid=03/02/25/1736237

Crucial part:

The claims include, 'The use of a hierarchical file system and an object repository for representing and hosting content and its structure,' and 'The combined concepts of file history, versioning, comparison, and merging as it relates to content, provide an archive of all individual changes as well as collections of changes so they can be versioned and audited.'