It is not part of the Microsoft DirectX9.0c specification. It is an IHV specific hardware feature, that just happended to be introduced at the same time as Shader Model 3.0.
Josh, you are mixig up FP16 pixel shader precision, in place since DX9.0 and continues on in DX9.0c with FP16 rendering. Two completely different beasts.
Josh, you are mixig up FP16 pixel shader precision, in place since DX9.0 and continues on in DX9.0c with FP16 rendering. Two completely different beasts.