Currently GlueGen has one C-Header parser frontend 
producing its intermediate representation (IR) objects.

It has been discussed to add an XML parser frontend,
allowing to read API specification using XML, 
e.g. Khronos OpenGL Registry
https://github.com/KhronosGroup/OpenGL-Registry

Relax NG schema for Khronos Registry XML
https://github.com/KhronosGroup/OpenGL-Registry/blob/main/xml/registry.rnc

Initially this frontend shall reproduce JOGL's 
GL profiles as currently done with C-Header for validation.

Later we may utilize it to produce other binding like Vulkan.