Any more info on D2D Custom Effect ?

Question

float4 main(
    float4 pos      : SV_POSITION,
    float4 posScene : SCENE_POSITION,
    float4 uv0      : TEXCOORD0
    ) : SV_Target
{
}

This is a Pixel Shader  in sample custom d2d effect, is there a default Vertex Shader, and what does the parameters mean?

The uv0(TEXCOORD0) seems not from 0.0 to 1.0 ?

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C++ DX11