When I was in law school, diligently learning the rules of legal citation, life was simple. There were the Federal Reporters. The old cases were in the series abbeviated "F.," the new cases were abbreviated "F.2d."
Similar rules followed for the Pacific series of reporters.
I feel vaguely uneasy when I see cases cited as "__ F.3d ___" and "___ P.3d ___". When did a third series of both these reporters sneak up on me? At my back I always hear Time's winged chariot running near.