The second direction opposes the first direction, {HEAD ~ the first voltage} has {TAIL ~ a different value} than the second voltage, and the first duration is substantially the same as the second duration 
has
The second direction opposes the first direction , { HEAD ~ the first voltage } has { TAIL ~ a different value } than the second voltage , and the first duration is substantially the same as the second duration
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH