Temporal data integrity may not seem mission critical in this particular instance (Zope as software project), but there are plenty of applications where such criteria are vital.
Mission critical -- no. Important -- yes. Internet RFCs use a simple but effective mechanism for managing temporal integrity. Each RFC has a unique ID and new RFCs that extend or obsolete old ones say so in their introductions (e.g. http://www.pmg.lcs.mit.edu/cgi-bin/rfc/view?number=822). Wouldn't it be great if "The (old) Product API Tutorial" http://www.zope.org/Members/Zen/howto/ProductAPITutorial said in its introduction "This HowTo has been superceded by "How to Create a Boring Product in Python" http://www.zope.org/Members/gtk/Boring/HowTo-Boring. This doesn't happen now, partly because there is no unique ID ("The (old) Product API Tutorial" was recently move from Amos' folder on the old site to Zen's folder on the new site, so any existing links between the two would have been broken) and partly because we have not established a policy and mechanism for doing so. But let's keep evolving (toward Xanadu?). How about enhancing the HowTo methods on www.zope.org (or perhaps on the next PTK-based version) to assign a system-generated unique ID to each HowTo at the time it's created (or cataloged).
Now appears a glimpse of the depths that Ted Nelson addressed in the
Xanadu
project. It may be time to review the sort of solutions that Xanadu actually applied to tracking documents changing over time. Does anyone have a complete collection of "Byte" from the 80's? There was an excellent article about Xanadu, and a fair exposition of the algorithm.