Definition: The storage and management of previous copies of a piece of information, for security, diagnostics, and interest.
Do you want version control? Can you reference a version only? If you refer to a particular place in a node, how does one follow it in a new version, if that place ceases to exist?
("Peter Aiken is the expert in this area" \u2014 Tim Oren, Apple)
Yes, at CERN we will want versioning. Very often one wants to correct a news item, even one of limited life, without reissuing it. This is a problem with VAX/NOTES for example. I would suggest that the text for the current version is stored, and separately those modifications necessary to backtrack to previous versions. I would expect previous versions to be regenerated only on the fly, as needed. (Apparently SCCS stores the original file and the differences. This system does allow you to distribute the differences when updating copies.)
If full differences (deltas) are kept, the first version is just the first delta from a null document. The latest version is not available without regenerating it from all the deltas. For speed, it is obviously useful to keep a copy of the latest version (see caching).
Versioning is necessary for accountability (\u2014David Durand, dgd@cs.bu.edu). If an author is to be accountable for information published, it should be possible to demonstrate later what he wrote, even if he has later changed it.
A WWW server may provide versioning, by allowing links between a document version and its previous and successive versions. This would be a good use of link typing.
Keeping track of versions allows one solution to the annotation problem.