Last modified: 2013-06-04 11:28:26 UTC
This seems to be a fact of life as new information is logged and data formatting is improved or extended. It would be nice if there was a way to look up how to interpret log events and when log formats switched. This is important for tracking user renames, page moves, blocks and grants. Right now, we tr to infer rules and changes by looking at raw data which is inconsistent at best.
This sounds like a documentation issue (perhaps something for the manual on mediawiki.org).