An abstract classifier is not a complete declaration and cannot be instantiated. It is used in definitions of other classifiers, like in generalizations, and in extend and include relationships.
A diagram presenting a control flow or a data flow. It focuses on sequences of actions and not on the instances performing the actions.
A role played by an entity outside a system, as perceived from the system's point of view, when it uses the system.
A class used in analysis models, usually less detailed than a class in a design model. Often, three kinds of analysis classes are used: Boundary class, Control class, and Entity class.
A model of a system that is independent of the implementation ...