{TAIL ~ a second set} of {HEAD ~ coefficients} equal to 1 extending away from said direction on said first side; and 
{ TAIL ~ a second set } of { HEAD ~ coefficients } equal to 1 extending away from said direction on said first side ; and
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH