Quote - BTW you will find plenty paraghraps like that in PZ3 so cannot tell you which one is the correct one.

You should be able to determine the correct one to modify as it will be the node input block belonging to the Poser_Surface node for that material.

So you'll first need to find the correct material section, then look for the Poser_Surface node, then for the Ambient_Value input (each of these will be a an increased nesting level).