Bip39 spec https://go.bubbl.us/ebe220/f17a?/Bookmarks The final action of BIP-39 is creating the particular binary seed and that is then applied as a learn crucial in BIP-32 deterministic wallet or working with other methods. For words that only have 3 letters, there isn't any 4th letter. As an example with the word https://bookmarkity.com/story20260997/bip39-dotmap-indicators-on-bip39-standard-you-should-know-https-linktr-ee-bip39