Bip39 json https://pixabay.com/users/51089543/ Though it employs BIP32 strategy you can continue to import BIP39 seeds into Electrum wallet. Also apart from BIp32 There may be BIP44 Model which some wallet use for the technology of seeds. For words that only have three letters, there's no 4th letter. As an example https://lingeriebookmark.com/story10008330/bip39-to-slip39-bip39-compatible-wallet-an-overview-https-dzen-ru-bip39-phrase-com