Bip-39 https://papaly.com/1/eMEf Although it works by using BIP32 approach you are able to however import BIP39 seeds into Electrum wallet. Also apart from BIp32 There is certainly BIP44 Edition which some wallet use with the generation of seeds. For words that have only 3 letters, there is absolutely no 4th https://ezmarkbookmarks.com/story20624543/bip39-buffer-is-not-defined-5-tips-about-bip39-standard-you-can-use-today-https-cutt-ly-uryc5rw7