Bip39 to slip39 https://www.4shared.com/s/fAf7kF4dLku The last move of BIP-39 is producing the particular binary seed which can be then made use of to be a master critical in BIP-32 deterministic wallet or making use of other solutions. For words that have only 3 letters, there is not any 4th letter. https://binksites.com/story10362631/bip39-s-entropy-to-mnemonic-the-smart-trick-of-bip39-word-list-github-that-no-one-is-discussing-https-linktr-ee-bip39