Hierarchical state machine = object-oriented programming in the SWE world. You'd have one state machine in each object. It's just rare to see that because even

Hierarchical state machine = object-oriented programming in the SWE world. You'd have one state machine in each object. It's just rare to see that because even the individual objects tend to have practically non-finite states, like counters and stuff, and just be too complex in general for FSMs. Maybe there's some math-ey way of saying everything we do is an FSM, but I don't think of it that way.