A method for providing writing requirements for a structured transition system employing state machines. The requirements employ a plurality of structuring mechanisms, namely, sub-state based structuring, abstraction based structuring and partial behavior structuring that uses event sequences. The sub-state based structuring has to do with the hierarchical requirements of the state machines, abstraction based structuring provides an abstraction of the state machines that reduces the number of states, and partial behavior structuring looks at certain states to predict how those states will affect other states.