Oh yeah, they were the 1st ever deterministic wallet, they also changed their dictionary and because of the versioning system this was fine.

Btw there was quite a bit of drama on the mailing list when BIP39 was being proposed between slush and Thosmas.

raw_avocado

bitcoin

Proposal for better BIP39

Interesting. The electrum wallet is using a versioning system for their seeds since forever. They mention the exact same reason - backwards compatibility.

https://electrum.readthedocs.io/en/latest/seedphrase.html