[UglyToad]

Good luck, I once started to scratch the same itch to learn this file format, several years later I think I got about 30% of the way through!

More open source PDF code is good. If you can find a version of iText RUPS application from somewhere on the internet it's a useful tool for viewing the syntax / structure.

[mdaniel]

> find a version of iText RUPS application from somewhere on the internet

You mean this, right? https://github.com/itext/i7j-rups#readme

[UglyToad]

Yes, that's the one. I found a compiled version somewhere because I was too lazy to install/learn Maven/Java stuff in order to build from source.