Bip39 Json. From this point forward the seed could be prepared on paper or spoken more than phone and this opened up new, Bodily means of backing up the seed (numerous paper copies in various places, strong copies on metal plates with more safety from hearth/flood etc.). The BIP39 standard https://pukkabookmarks.com/story18675332/bip39-passphrase-about-bip39-mnemonic