use punched cards
format and meaning are left to interpretation of the reader
https://en.wikipedia.org/wiki/Punched_card#Card_formatsIts clear punched cards are not the universal storage medium to last a century and you'll need special equipment to interpret it.
Books are vulnerable to rot and insects.
The only guaranteed data storage is metal engraving, and it has to be on corrossion resistant stuff to last centuries - however its expensive and slow to reproduce.
The ideal data storage format would visible text on some sturdy yet mutable surface.
Something like this, but for technical knowledge sufficient to bootstrap logical abacus/slide rule/analog computer industry and minimal technology.
https://en.wikipedia.org/wiki/World%27s_largest_book