Extension points

In UML models, an extension point identifies the point in the base use case where the behavior of an extension use case can be inserted. The extension point is specified for a base use case and is referenced by an extend relationship between the base use case and the extension use case.

A base use case can have several extension points. Each extension point has a unique name that identifies one or several locations in the behavior sequence of the base use case.

As the following figure illustrates, the name of the extension is listed in the Extension Points compartment of the use case.

An extension point shown below the name of the use case