UML Standard Profile
tag definition usage
Usage applies only to transitions leading into or out of an object flow state. It has a value of uses or modifies. A value of uses indicates that the action of the state at the other end of the transition from the object flow state uses but does not modify the object represented by the object flow state. A value of modifies indicates that the action of the state at the other end of the transition from the object flow state modifies and may use the object represented by the object flow state.