Bip39 Checksum. The passphrase is not really picked within the predefined list of 2048 words – it might be any word or phrase you select. BIP39 is really a structure implementation that lays out how copyright wallets produce the set of words (or "mnemonic codes") which make up a mnemonic https://bookmarkwuzz.com/story19110366/bip39-wallets-https-linktr-ee-bip39-5-essential-elements-for-bip-39