glXCreateContextAttribsARB: fb config compatibility
===

OpenGL doc states that
> If glXCreateContextAttribsARB succeeds, it initializes the context to
> the initial state defined by the OpenGL specification, and returns a
> handle to it. This handle can be used to render to any GLX surface
> (window, pixmap, or pbuffer) compatible with <config>, subject to
> constraints imposed by the OpenGL API version of the context.

How do I determine compatibility of different framebuffer configurations?
Thank you.