There is one for genre, but modeling isn't really a genre unless photography and 2D are (and they are listed as topics, not genres). I think this is a request to put allow those who do modeling with programs other than Rhino or Truespace or the like some place aside from "other apps" to tag their works. That would enable the combination of "modeling plus science fiction," for example, instead of limiting it to "other apps plus modeling," which seems less descriptive.