The StateMachines shown so far only had Transitions between States on the same level, that is, on the same StateMachine. Of cause, it is possible and often required to have Transitions between States of the StateMachine and States of its SubStateMachine.
Because a SubStateMachine can be defined by another StateMachineType and this type can be used in several places, it is not possible to add a bi-directional Reference from one of the shared States of the SubStateMachine to another StateMachine. In this case it is suitable to expose the FromState or ToState References uni-directional, that is, only pointing from the Transition to the State and not being able to browse to the other direction. If a Transition points from a State of a SubStateMachine to a State of another sub-machine, both, the FromState and the ToState Reference, are handled uni-directional.
A Client shall be able to handle the information of a StateMachine if the ToState and FromState References are only exposed as forward References and the inverse References are omitted.
Figure 10 gives an example of a state machine having a transition from a sub-state to a state.
Figure 10 – Example of a StateMachine with Transitions from sub-states
In Figure 11 the representation of this example as StateMachineType in the AddressSpace is given. The "Transition1", part of the definition of "MyStateMachineType", points to the "StateX" of the StateMachineType "AnotherStateMachineType". The Reference is only exposed as forward Reference and the inverse Reference is omitted. Thus, there is no Reference from the "StateX" of "AnotherStateMachineType" to any part of "MyStateMachineType" and "AnotherStateMachineType" can be used in other places as well.
Figure 11 – Example of a StateMachineType having Transition to SubStateMachine