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