The reference map transformation values are used in {HEAD ~ conjunction} with {TAIL ~ a terrain correlation process} to establish vehicle position 
The reference map transformation values are used in { HEAD ~ conjunction } with { TAIL ~ a terrain correlation process } to establish vehicle position
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH