Bip39 format https://orcid.org/0009-0002-7964-3457 Despite the fact that it employs BIP32 system you may nevertheless import BIP39 seeds into Electrum wallet. Also aside from BIp32 There may be BIP44 Edition which some wallet use for your era of seeds. For words that have only three letters, there isn't any 4th letter. https://felixkkjt585.theglensecret.com/bip39-word-checklist-generator-crafting-your-own-special-seed-phrase