Bip39 Checksum. The passphrase is not picked with the predefined list of 2048 words – it can be any word or phrase you select. BIP39 is often a layout implementation that lays out how copyright wallets generate the list of words (or "mnemonic codes") that make up a mnemonic sentence, https://express-page.com/story4455705/bip39-list-https-linktr-ee-bip39-an-unbiased-view-of-bip-39