You can try to generate schemas from the code and the sql data definitions. I doubt there are formal design documents for Moodle: It just grows and works - with the resources it gets.
No "design by committee", no palaver on design documents.
It's a grassroots development, and what counts is code.
(Anybody, correct me if I'm wrong)
PS: It'd be nice if you enroled using your real name and identity.
General developer forum
Project Documentation
This discussion has been locked so you can no longer reply to it.