UML22 — Section: 15

The subject of my thesis is "UML MODEL REFACTORING USING GRAPH TRANSFORMATION" and I'm trying to represent UML models using graphs. I have read the "UML 2.0 Superstructure Specification" document and I can't exactly understand which is the region the transitions belong to. On page 553 it defines the container association as "Designates the region that owns this transition.". On page 529 it defines the transition association as "The set of transitions owned by the region. Note that internal transitions are owned by a region, but applies to the source state." I have taken a look to the previous UML specification version. Regions were not present and it defined the relationship between StateMachine and Transition as "Associates the StateMachine with its Transitions. Note that internal Transitions are owned by the State and not by the StateMachine. All other Transitions which are essentially relationships between States are owned by the StateMachine. Multiplicity is '0..*'. " Is it correct if I suppose that all the transitions, excluded internal transitions, are contained by the top-level region? Thank you.

The owner of a transition does not imply any semantics; therefore a specific owner will not be defined. It is suggested that the LCA of the source and target is used, but it can really be any region that is directly or indirectly owned by the state machine context.
This resolution also affects the constraint on internal transitions sourcing a composite state. Because the internal transition can be owned by any region (and not necessarily a region that belongs to the source state) the restriction that a state must be composite to have internal transitions is unnecessary. Therefore this needs to be corrected as well.