The magnitude of delay is varied between these two extremes by varying {TAIL ~ the relative levels} of operation of the differential sections D1 and {HEAD ~ D2} 
The magnitude of delay is varied between these two extremes by varying { TAIL ~ the relative levels } of operation of the differential sections D1 and { HEAD ~ D2 }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD