Use Case Extension Points

The behavior defined for a Use Case can add to the behavior of another Use Case; that is, the first Use case extends the second one. This is represented on the model by an Extend connector from the first Use Case to the second. If the extended behavior takes effect at a specific point, you can define that point as an extension point on the extended Use Case. The name (description) text of the extension point can be as informal or precise as is appropriate to define the point in behavior at which the extension applies. A Use Case can have more than one extension point, to allow for different source Use Cases to extend this target Use Case, or for changes in where the extending behavior applies depending on the constraints defined for the Extend connector. The connector also identifies which extension point is in effect.

Access

Context Menu

On diagram | Right-click on extended Use Case element | Advanced | Edit Extension Points

Add extension points to a Use Case

Field/Button	Action
Defined Extension Points	Lists the extension points currently defined for the selected Use Case.
Add	Click on this button to display a prompt for the name of a new extension point. Type the name and click on the OK button. The name is added to the Defined Extension Points list.
Edit	Click on an existing extension point and click on this button to display a prompt for changes to the name of the selected extension point. Overtype the name and click on the OK button. The name is updated in the Defined Extension Points list.
Remove	Click on an existing extension point and click on this button to immediately remove the name from the Defined Extension Points list.
OK	Click on this button to save all changes to the extension points, and to close the dialog. The extension points you have defined are represented on the Use Case element in the diagram as shown.

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