An extension relationship can only reference Extension Points from its targeted Use Case.


An Extension Point is a feature of a Use Case that identifies a point where the behavior of a Use Case can be augmented with elements of another (extending) Use Case. Therefore, the referenced Extension Point must be part of the extended Use Case, which is the target of the extension relationship.


  • Choose another Extension Point to reference. This must be part of the extended Use Case.
  • Otherwise, make the extension relationship target the Use Case containing the referenced Extension Point.