Furthermore, {TAIL ~ the separation} between {HEAD ~ a pair} of adjacent rows need not be equal to the separation between another pair of adjacent rows 
Furthermore , { TAIL ~ the separation } between { HEAD ~ a pair } of adjacent rows need not be equal to the separation between another pair of adjacent rows
OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH