UMLR — Actor Relationships

It is very confusing to understand that an Actor may be a generalization of another Actor on a Use Case model of a system. An example of this is not provided in Section 18. To understand this, you need to trace up and back down the document and understand Actor, BehavioredClassifier, Classifier, Generalization, DirectedRelationship, Relationship, Association to see that a Generalization is not an Association.

In section 18.2.1.4, the UML specification states: "An Actor can only have Associations to UseCases, Components, and Classes. Furthermore these Associations
must be binary."

In Section 18.2.1.3, the same document states that an Actor is a BehavioredClassifier. A BehavioredClassifier is also a Classifier.

Section 9.9.4.6 defines the association ends for a Classifier. One of these relationships is Generalization.

Section 9.9.7 defines the Generalization relationship. The generalization of a Generalization is a DirectedRelationship.

Section 7.8.5 defines DirectedRelationship. The generalization of a DirectedRelationship is a Relationship.

Section 7.8.15 defines the Relationship abstract class. The specializations of Relationship are DirectedRelationship and Association.