M4 base (just load the figure) does not have a "shader" - it is just color texture plugged into Diffuse_Color, which is set to white.

But there is a mat-pose file that loads a shader. This shader has a blue tint in the Diffuse_Color. The purpose is to remove some of the overall baked-in red of the color map, and then add red back selectively based on the lighting so as to make some semblance of sub-surface scattering in the skin. The redness is added using a Color_Ramp node driven by a Diffuse node to measure the amount of light hitting the surface.

This technique was introduced by me and then later discredited by me. But Daz has been using it ever since.

It works for many lighting situations, but not all, and the shader totally blows up if you're rendering with Poser Pro gamma correction turned on.

However, it isn't always blue - and sometimes it is too red. So it all depends on your lighting.

Since then, I've come up with better ways to render skin.

Here is a comparison, with my default lights, not Poser's default.

Left is plain no-shader M4. Middle is M4 with his Daz supplied shaders. Right is M4 with my free VSS shaders.

Which one do you think you should be using?

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)