R510 - modelint/shlaer-mellor-metamodel GitHub Wiki
R510 / Generalization
State is a Real State or Initial Pseudo State
Multiple Transitions may or may not be defined to exit a Real State, while an Initial Pseudo State requies at least one Transition on some Effective Event.
So all State's represent a source of a Transition.
A Real State, in addition, must execute a State Activity upon entry.