I agree with Myfist0, I think it is material shading in Sins. Colour(as you so correctly pronounced) 0 is black. Which is why models in Sins appear completely black when they have no textures attached, I think anyway.

I guess you could give it a value and test a model with no textures to prove this theory.

You are probably right. It may have had some purpose in development and then it was thought not necessary later.

Another thing in the mesh file that I have been wondering about whether it can be used is the displacement texture option. On the next model I make, I will make a displacement map and try to hook it up. Not sure what it needs to plug into on the shader node though as yet. I can hook them into the material node. not sure whether that'll work in Sins though.

It may also have always been redundant to Sins engine, and that is just there from the .xsi file which has those options if needed.