i'm trying rendermonkey for shader coding and there is the possibility to export the shadercode as .fx

if i look at the code in SED i see there are many variables SED do not understand. is there a way to use another compiler with SED or is it hardcoded. for example .fx code:

Code:
float invMaxDepthC: register(c0);
// Simply output the inverse of the maximum depth complexity expected.
// With additative blending and no depth compares it will accumulate
// to a number in the range [0..1] indicating the depths at each pixel.

float4 main() : COLOR 
{
   return invMaxDepthC;
}


here the 'register' does not compile. what could help then?