UML Quality


I dont think the relevance of this question to any tool, My question is little bit general, I floated this question here because I found this forum very useful and also good expert opinions.
My question is related to the Usage of UML models, in the sense of a quality model like most popular quality model is a McCall model. It has three uses Product Operation, Product Transition and Product revision. First two have relevance to the system not to the models and the last one is basically a maintenance of the product, and which can easily be considered for the UML models. So I can say here that Product revision i.e maintenance is a pure use of UML models.

Do you have any other idea, which can be considered as a UML usage and which can be further sub categorized to measure the quality of UML models.