Well, not to be overly nitpicky, but the term "material groups" as applied in this context is used throughout the Poser manual, so it seems clear to me what is meant. :)

In any case, what I would do (if I understand you right) is edit the pp2 / cr2 file and change the name of whatever material, and then edit the OBJ file (if there is one involved) and change the name there as well.  Search and replace does the trick, or if you use some high power poser file editor like Dimension3D's, they may have features bult in to do just this (Dimension3D's does).

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