OpenGL 1.4 will provide a unified instruction set and way of calling it. Right now neither exists. For more capabilities which exploit arbitrary stages, resource, and branching capabilities across multiple platforms you need to hide some of the implementation details. There are all sorts of things which might comprise an instruction in a low level graphics library, for example a LUT might supply an arbitrary function in a single operation, a blend, alphatest or stencil op might be a branch. Do you want to have to implement that LUT using whatever strange hardware is available on 3 or more platforms in an implementation or do you want to just request the function or operation in a higher level language and have the guys at NVIDIA, ATI and 3DLabs implement it as best they see fit on their implementation?
You will get the basics in OpenGL 1.4, but there is a growing need for something more powerful that hides the implementation details.
[This message has been edited by dorbie (edited 05-06-2002).]