{TAIL ~ a third set} of {HEAD ~ coefficients} equal to −1 extending away from said direction on said second side 
{ TAIL ~ a third set } of { HEAD ~ coefficients } equal to −1 extending away from said direction on said second side
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