Bip32 and bip39 https://go.bubbl.us/ebe220/f17a?/Bookmarks While it takes advantage of BIP32 strategy it is possible to even now import BIP39 seeds into Electrum wallet. Also besides BIp32 there is BIP44 version which some wallet use to the generation of seeds. For words that only have three letters, there isn't any 4th https://freebookmarkpost.com/story20560187/bip39-word-list-github-about-bip39-2048-words-https-www-youtube-com-channel-ucupxfytj0fb78sq55hu6ocw