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