My question has mainly answered itself by an older thread, where I found that the Gamestudio interface follows the Direct specifications - outlined in the EffectFile descriptions (which you will find in the DirectX manual).

Nevertheless - there is a follow up question.
Gamestudio reported syntax errors - although the code fulfilled DirectX szandards (or was copy pasted).
For example: Trying to define a VertexShader constant would not work.

Does the interface fully support the Graphic effects? Are there restrictions? Which?