In one example, the end of {HEAD ~ preamble} can occur only when the state machine is in {TAIL ~ two of four states} 
In one example , the end of { HEAD ~ preamble } can occur only when the state machine is in { TAIL ~ two of four states }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL