Why the GPL?

Why not use the Creative Commons licence?

CC-licensed books tend to be a complete licensing mess, where various parts of the book can be covered under different CC licences. I don’t want people to deal with a patchwork of legal questions. I want everyone to just make and copy the changes they want.

CC licences also don’t protect the source files, so they can’t guarantee that anyone can actually copy anything.¹

So why use the General Public Licence, which is made for coders?

Firstly, the GPL explicitly states it is for “programs and other projects”.

Secondly, BIND has actual code. The statblocks and layout have code to put the book together.

Why not use the CC-BY licence on the source files then?

That would mean that the PDF changes would be under the CC-BY licence, but not the code modifications (which is what you need to actually use those changes). The CC licences does not handle the distinction between the output and source files.

Can’t you use the CC licence for images at least?

Why complicate things with two licences? Besides, lots of programs contain images and other assets. The GPL covers them just fine.

What about the GNU Free Document Licence?

I suspect that everyone who has suggested using GFDL hasn’t read it. It’s a turgid, awful read, and it seems to state that I would have to re-print the entirety of the GFDL within the output. For a book, that means including some pointless ‘Appendix C: Licence’, which nobody will read. And I don’t know what it means for character sheets - should I reprint the GFDL on a character sheet if that’s an output file?

Also, I don’t fully understand the GFDL. I can’t apply a licence I don’t understand.