determining a first positive transition temporal relationship of {HEAD ~ the first positive transition} to {TAIL ~ a first reference positive transition time}; and 
determining a first positive transition temporal relationship of { HEAD ~ the first positive transition } to { TAIL ~ a first reference positive transition time } ; and
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH