{TAIL ~ Such an equation} can also be used directly for the 3 D reference model during {HEAD ~ run time}, as further described below 
{ TAIL ~ Such an equation } can also be used directly for the 3 D reference model during { HEAD ~ run time } , as further described below
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH