Bip39 checksum https://list.ly/abregeouoh The final action of BIP-39 is creating the particular binary seed and that is then applied to be a grasp important in BIP-32 deterministic wallet or making use of other methods. For words that only have three letters, there isn't a 4th letter. For instance Using the https://www.anobii.com/en/01000289012ff9b293/profile/activity