Bip39 Seed. If you would like to refresh your memory about the basics of how copyright wallet seed phrases and passphrases do the job, look at reviewing the Vault12 report in regards to the BIP39 standard. For words that have only three letters, there is absolutely no 4th letter. One https://directoryforever.com/listings13057401/bip39-list-https-linktr-ee-bip39-5-simple-statements-about-bip39-compatible-wallet-explained