Bip39 rules https://josueaqpi312.huicopper.com/leading-5-online-bip39-generators-for-easy-copyright-security Although it takes advantage of BIP32 approach it is possible to however import BIP39 seeds into Electrum wallet. Also besides BIp32 There is certainly BIP44 Variation which some wallet use with the generation of seeds. The amount of security does a passphrase add? A BIP39 passp... https://madbookmarks.com/story20046834/bip39-golang-a-secret-weapon-for-bip39-mnemonic-code-converter-tool-https-linktr-ee-bip39