Bip39 Solana. From this level forward the seed could be published on paper or spoken about telephone and this opened up new, Actual physical ways of backing up the seed (various paper copies in several locations, long lasting copies on steel plates with added security from hearth/flood etcetera.). This file https://bookmarkize.com/story18660804/bip39-dot-map-the-definitive-guide-to-bip39-standard