^this isn't true. L-Canceling has always been short for Lag-Canceling, and tbh I highly doubt there was any sort of widespread L-Canceling in 64 before Melee came out. There wasn't any reason to get good at it because the Melee era is what invented the concept of hosting, attending, and traveling to tournaments. Metagame didn't really develop because the internet was in its baby stages. Etc. etc.
My source: directly from Isai who has been at the top of the n64 metagame since before melee came out and i believe he was part of the early melee tournament scene as falcon as well.
Think about it. why wouldn't people call it lag cancelling instead of l cancelling if that's what it stood for. Lag cancelling is the same amount of syllables as L cancelling, it doesn't even shorten it.
Of course there was widespread z cancelling in high level n64 play before melee. It's not that hard to find out by accident after playing seriously for a couple months, especially if you play link (I know several people that found it out by accident in the early stages of smash just by trying to shield when they hit the floor with his terribly laggy Dair). Remember that in smash 64 the window for z cancelling is 20 frames, not the 7 frames in melee.
Also, if it really was short for lag cancel, then why is it 100% completely consistently called z cancelling by n64 smashers and not l cancelling? The only time I've heard someone say L cancel for smash 64 was when they were meleers coming over to advanced SSB for the first time.
There's my evidence. Where's yours?