The method 7, wherein a portion of said non SATPS position determination data is acquired by {HEAD ~ an instrument} for sensing {TAIL ~ a magnetic field} 
for sensing
The method 7 , wherein a portion of said non SATPS position determination data is acquired by { HEAD ~ an instrument } for sensing { TAIL ~ a magnetic field }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL