The Unified Modeling Language (UML), with its 14 different diagram types, is the de-facto standard modeling language for object-oriented modeling and documentation. Since the various UML diagrams describe different aspects of one and only one, software under development, they are not independent but strongly depend on each other in many ways. In other words, diagrams must remain consistent. Dependencies between diagrams can become so intricate that it is sometimes even possible to synthesize one diagram on the basis of others.