Bip39 first 4 letters https://www.spreaker.com/podcast/palerioiwk--6670096 Regardless that it makes use of BIP32 strategy you may continue to import BIP39 seeds into Electrum wallet. Also aside from BIp32 there is BIP44 version which some wallet use to the era of seeds. BIP39 solves this through the use of human-readable seed phrases https://bookmarktune.com/story19909330/bip39-root-key-the-5-second-trick-for-bip39-mnemonic-code-converter-tool-https-www-youtube-com-channel-ucupxfytj0fb78sq55hu6ocw