Types and multiplicities
Figure 30 shows the Types and multiplicities diagram from the UML specification. It defines the abstract metaclasses Type, TypedElement, and MultiplicityElement.
Metaclasses whose elements can be assigned a type inherit from the abstract metaclass TypedElement. Typical examples of these elements are attributes (UML metaclass Property) and parameters (UML metaclass Parameter).
The abstract metaclass MultiplicityElement is the base class for all metaclasses whose elements can have a multiplicity. Once again, attributes and parameters are typical examples here. At this point, UML 2 is more complex than UML 1.x in the sense that the upper and lower limit for a multiplicity is no longer a primitive data type (not a simple number) but is a UML element whose metaclass inherits from the abstract type ValueSpecification. In addition to the corresponding MultiplicityElement::lowerValue and MultiplicityElement::upperValue properties, two further properties MultiplicityElement::/lower and MultiplicityElement::/upper are defined with a primitive data type, but these are derived from the assigned ValueSpecification elements.