Word List Bip39. The sole purpose those letters are listed is to make it a lot easier for our human brains to study them and possibly memorize our recovery phrase. These words are pulled from a specific list of 2048 words. They can be found in this article or listed https://thebookmarknight.com/story18758192/bip39-word-list-ledger-the-definitive-guide-to-bip39-standard