Bip39 Regex. The only cause Individuals letters are listed is to make it a lot easier for our human brains to read them And maybe memorize our recovery phrase. Sharing your seed's location with some other person and not worrying about them being able to just take your funds. Entropy https://deannyisc.wikimidpoint.com/4569306/the_anatomy_of_a_bip39_phrase_entropy_terms_and_safety