What does Multi Material do

[SHoutzager]

When you go in the Material Editor, >Create Material >MultiMaterial it creates a way to combine in a list several materials and rearrange the order. What is this used for? Only the top is rendered out.

On a slightly different note, I know that VRay 3 for max allows you to take two materials and control the blend between them in the way that Photoshop does. That is with multiply, overlay, etc. Where is this in the Rhino version?

[fpedrogo]

The multimaterial is only for proxy. The proxy object have different materials ID. Rhino recognize those IDs and assign the corresponding material.
V-Ray for Rhino do not have V-Ray Blend material yet. It will be implemented for V-Ray for Rhino 3.0