An Extend Use Case indicates how and when the behavior defined in the extending Use Case can be inserted into the behavior defined in the extended Use Case. The Extend relationship is a relationship for an extending Use Case to the extended Use Case. An Extend relationship can have a condition. If the condition is true, then the Extend action is performed.
Example of Extend relationship
The extended Use Case owns one or more specific extension points. An extension point identifies a point in the behavior of a Use Case where that behavior can be extended.
In the preceding example, the Penalize for Overdue Use Case extends the Register Item Return Use Case. The Register Item Return Use Case owns the Return Violation extension point.
You can format the extend symbol properties in the Symbol Properties dialog.
You can specify Extend properties in the Extend Specification window. You can find the description of each property In the same window. Descriptions are presented in the description area of the Specification window.
Editing property values
For more information about specifying property values, see Editing property values.
Example of the Use Case diagram in <MagicDraw installation directory>\samples\diagrams\use case diagram.mdzip.