Bip39. The seed phrase may be transformed into a quantity that is made use of since the seed integer to the deterministic wallet that generates many of the crucial pairs Employed in the wallet. For words that have only three letters, there isn't any 4th letter. By way of example https://directoryalbum.com/listings13170364/bip39-https-linktr-ee-bip39-the-best-side-of-bip39-list