Bip39-Standalone. The passphrase will not be chosen through the predefined list of 2048 words – it could be any word or phrase you decide on. BIP39 is usually a layout implementation that lays out how copyright wallets produce the list of words (or "mnemonic codes") that make up a mnemonic https://checkbookmarks.com/story4385135/bip39-words-https-linktr-ee-bip39-top-guidelines-of-bip39-passphrase