http://www.daz3d.com/forums/viewthread/29367/

It's called "mixer" it's an option in the color channel of a shader. You can use the texture overly on the skin with the mixer.

There is also new in C8.5 the mixer shader that allows you to mix 2 shaders using a mixing or distribution map. Great for when you want a metalic shader with a nonmetalic shader. Say actual gold accences on clothes. Or say you want your poser figure to have a couple of gold teeth.