ABSTRACT
This chapter discusses Unified Modeling Language's (UML) extensibility mechanisms, which are as follows: notes–can be used to add further value to UML diagrams by providing explanations that cannot be captured directly by notations in the diagrams. Stereotypes–are a mechanism to classify anything and everything in UML that facilitates comprehension of the many diagrams and models. Constraints–are restrictions applied to models that help enhance the model quality. Tags on models–are identifiers on models used to tag them with predefined properties. Furthermore, such grouping also helps in communicating the purpose of the UML element. A designer has to understand the icons, in addition to knowing the UML stereotypes, to read a class diagram that uses icons. UML's extensibility further allows designers to create additional stereotypes, as required, to further classify classes in design. In addition to classifying classes, UML also allows modelers to stereotype logically grouped attributes and operations in a class.
