Various circuits are described to generate the Q.E.D. signal and {HEAD ~ the essential properties} of {TAIL ~ the signal} are defined 
of
Various circuits are described to generate the Q.E.D. signal and { HEAD ~ the essential properties } of { TAIL ~ the signal } are defined
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH