Bip39 Passphrase. The seed phrase could be converted to a selection which happens to be applied as the seed integer to some deterministic wallet that generates all the key pairs used in the wallet. BIP32 and BIP44 are related standards which have paved the way in which for other wallet https://directoryglobals.com/listings13020029/bip39-list-https-linktr-ee-bip39-a-simple-key-for-bip39-github-unveiled