Classes
Figure 37 shows an extract from the Classes diagram supplemented with content from the Structured Classifiers and Encapsulated Classifiers diagrams in the UML specification. The central metaclass in this diagram is Class. The three abstract base classes BehavioredClassifier, StructuredClassifier, and EncapsulatedClassifier are only included here to illustrate the inheritance relationship between Class and Classifier. They define additional properties that will not be discussed further in this introduction.
The diagram also shows that attributes (UML type Property) can theoretically be assigned to all classifiers using the derived property Classifier::/attribute. The type of the specific assignment is defined by the corresponding specializations. For the Class metaclass it is the compositional property ownedAttribute. An example of the representation of attributes in classes is shown in Figure 36.