All state machine types defined in this specification are mandatory unless explicitly stated otherwise. However, some states may be implemented as transient (do-nothing) states depending on the characteristics of the vision system.
To improve clarity and re-usability, this specification makes use of hierarchical state machines. This means that states of a state machine may have underlying SubStateMachines. The instantiation of a SubStateMachine for a particular state of the main state machine may be specified as optional.