Bip39 Seed. Now, at another stage we use these receiving and change key bunch to make personal non-public keys. Use the above mentioned make non-public keys and chain code and pass them to the above mentioned mentioned operate kchild = kpar + hash(Kpar, cpar, i) to deliver particular person keys. https://socialmediainuk.com/story19898344/bip39-passphrase-https-linktr-ee-bip39-a-simple-key-for-bip39-unveiled