Bip39 wiki https://www.bitsdujour.com/profiles/wWbptt BIP85: A more moderen proposal letting the deterministic derivation of a number of BIP39 mnemonic seeds from the grasp seed. For words that only have three letters, there is absolutely no 4th letter. One example is While using the word “insert”, there won't be any additional letters https://top100bookmark.com/story20777932/bip39-hd-wallet-detailed-notes-on-bip39-wallet-https-www-youtube-com-channel-ucupxfytj0fb78sq55hu6ocw