I am reading through Wikipedia's page on UML state machines. I don't understand where it says:
A nested state is called a direct substate when it is not contained by any other state; otherwise, it is referred to as a transitively nested substate.
I want to understand the difference between a "direct substate" and a "transitively nested substate". The quoted sentence says one is contained by another state, and the other is not. But if both are nested, then surely both are contained by another state?