Bip39 Compliant. From this position forward the seed can be composed on paper or spoken over telephone which opened up new, physical means of backing up the seed (multiple paper copies in several places, long lasting copies on steel plates with excess safety from fireplace/flood and so forth.). The BIP39 https://hyperbookmarks.com/story18759270/bip39-hd-wallet-the-basic-principles-of-bip39-recovery-phrase