yes, they've worked that out.  assign a material zone to each group and then run one of the scripts that gives a different colour to contiguous zones.  they use it for texture seams.  but this "smoothing group" appears to be something else.  like if one is doing a smooth-shaded preview and one wants creases to appear somewhere away from a body part edge, in an analogous way to setting the same toon ID so there will be a line between groups that are to use a different toon shader.  the main place where the new group names appear is in deformer zone dropdown lists.  I don't see anywhere to set smoothing and crease angle for the new group.  I don't see any python variables for it, either.