:Great Renaming: n. The {flag day} in 1985 on which all of the
non-local groups on the {USENET} had their names changed from
the net.- format to the current multiple-hierarchies scheme. Used
esp. in discussing the history of newsgroup names. "The oldest
sources group is comp.sources.misc; before the Great Renaming,
it was net.sources."
-- The AI Hackers Dictionary