We will use the same notation and terms of the ordinary FSMs, but some new notation to represent recursive states and variable transitions. First, we permit a new type of transition, as shown in Figure 7; (from state C to A), this is called the Recursive Transition (RT).
A recursive transition arrow (RTA) from one state to another means that the transition from the first state to the second state is done by a recursive call to the second one after changing the Variable Transition Vector. Second, the transition condition from a state to another may contain variable parameters according to the current level, these variable parameters are distinguished from the constant parameters by the notation V(parameter name). All variable parameters of all state transitions constitute the Variable Transition Vector. It should be noticed that nondeterminism is not allowed, in the sense that it is impossible for two concurrent transitions to occur from the same state. Figure 8 is the equivalent FSM representation (or the flat representation) of the DRFSM shown in Figure 7, for three levels, and it illustrates the compactness and efficiency of the new notation for this type of process.
