I hope this is what you are looking for...just asked the OpenGL IRC.
They told me they are listed in the xml files in this folder

https://cvs.khronos.org/svn/repos/ogl/trunk/doc/registry/public/api/

and can be parsed.

Or in glcorearb.h
https://cvs.khronos.org/svn/repos/ogl/trunk/doc/registry/public/api/GL/glcorearb.h

Hope that helps,

Walter