Bip39 last word checksum https://list.ly/abregeouoh Though it works by using BIP32 process you could nonetheless import BIP39 seeds into Electrum wallet. Also aside from BIp32 There's BIP44 Edition which some wallet use to the technology of seeds. For words that only have 3 letters, there is no 4th letter. For https://monobookmarks.com/story20390142/bip39-test-vectors-not-known-details-about-bip39-word-list-txt-https-www-youtube-com-channel-ucupxfytj0fb78sq55hu6ocw