Writing an OpenGL extension

I’ve found a lot of information about the administrative procedures for registering opengl extensions, but I haven’t found any useful information about how to go about writing an extension. For instance, is it simply a collection of procedures or does it have access to the context? Can someone point me in the right direction?

You need access to the ogl driver source. Assuming you have that, you need to add a function to your proc table which gets referenced from microsoft’s opengl32.dll. For linux I assume you can skip the whole proc table and just create an entry point function.