Great Renaming

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."