Bip39 Checksum. The passphrase will not be picked from the predefined list of 2048 words – it could be any word or phrase you end up picking. Mnemonics are representation of entropy. Initial step requires earning a decision as to the amount of entropy you consider Risk-free on your functions. https://socialbuzzfeed.com/story5126218/bip39-list-https-linktr-ee-bip39-not-known-details-about-bip39-wallets