No text, but a visual code

[-JKP-]

That's what I meant by "coordinates". That would describe their position in the sky, although typically they did this by drawing the constellations and adding stars to their locations. But if they wanted to add mathematical coordinates (which some did), it still wouldn't account for so many pages.

And then there are the plant folios. The only thing they really cared about was which celestial body governed the plant. If the plant info is related to the pics, that only takes one or two words.