In general, all rules on subtyping apply for StateMachinetypes as well. Some additional rules apply for StateMachinetypes. If a StateMachine type is not abstract, subtypes of it shall not change the behaviour of it. That means, that in this case a subtype shall not add Statesand it shall not add Transitionsbetween its States. However, a subtype may add SubStateMachines, it may add Transitionsfrom the Statesto the Statesof the SubStateMachine, and it may add Causesand Effectsto a Transition. In addition, a subtype of a StateMachinetype shall not remove Statesor Transitions.