Bip39 checksum http://www.mediafire.com/file/uilrjfajg2ami24/pdf-14673-57158.pdf Though it employs BIP32 system you can even now import BIP39 seeds into Electrum wallet. Also besides BIp32 There exists BIP44 version which some wallet use for the technology of seeds. Some wallets can import a variety of seed phrases plus some have only just one standard. https://thebookmarkage.com/story20386383/bip39-npmjs-bip39-github-an-overview-https-cutt-ly-uryc5rw7