Bip39 nedir https://writeablog.net/ipennywpzc/the-ultimate-overview-to-offline-bip39-generators-remain-secure While it takes advantage of BIP32 method you can continue to import BIP39 seeds into Electrum wallet. Also apart from BIp32 There exists BIP44 Variation which some wallet use to the generation of seeds. For words that only have 3 letters, there is absolutely no 4th letter. https://bookmarkgenious.com/story20326585/bip39-word-list-how-many-words-bip39-npm-no-further-a-mystery-https-dzen-ru-bip39-phrase-com