In this context, {HEAD ~ the coordinate system} 100, 101, 102 can be {TAIL ~ a geographic position}, for example, including elevation 102 
be
In this context , { HEAD ~ the coordinate system } 100 , 101 , 102 can be { TAIL ~ a geographic position } , for example , including elevation 102
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH