Source Code Documentation
The OpenVAS team uses doxygen for source code documentation.
Note, that you can produce the full and alternatively a light documentation on your own by using the command "make doc-full" or "make doc" in the module's source main directories. The doxygen support has been added shortly after the 2.0.0 releases, so you won't find these make-targets for older releases.
Because of the size of the full documentation, the website offers only the documentation of the most recent release for each module.