That’s pretty typical of binary formats. That and offsets or addresses. And type tags. Assuming the payload isn’t compressed or encrypted, you can get pretty far assuming you’ll run into one of those eventually.

Anecdotally, earlier today I was trying to decipher Encarta data and came across the “Mind Maze” data and it’s mostly that - fixed 32-but header, question size, (answer size, answer, correct flag, something I haven’t figure out yet){4}. Then a separate file with an index value and an offset into the first file as well as a header I haven’t figured out yet.