A cycle is defined by repeatedly developing {TAIL ~ a start signal} at {HEAD ~ the beginning} of each cycle 
A cycle is defined by repeatedly developing { TAIL ~ a start signal } at { HEAD ~ the beginning } of each cycle
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH