Libcanard return codes

I’ve been looking at the libcanard C implementation and wondering what standard is being followed for return integers of functions.

I’m also curious as to what “extent” means- is that the maximum capacity of the allocated payload pointer? The “Capacity” of sorts?

OK, I just figured out how C headers work. Looks like all the documentation is there in canard.h. Was wondering why the source code was so sparsely documented.