WE CREATE A ROUTE WHICH EQUAlS A SPECIFIC FIElD-THEN WHIlE DRIVING THROUGH THE FIElD (WITH THE UNIT MAKING TRACKS)WHERE YOU SPOT A ROCK OR OTHER SPOT YOU WANT TO INDENTIFY lATER YOU MARK A WAYPOINT AND IDENTIFY IT--lATER YOU CAN GO BACK TO THAT SPOT. IT WORKS BEST ON A OPEN VEHIClE HOWEVER AS lONG AS YOU GET THREE SATAlITES YOU CAN MARK. THE MORE SATAlITES THE ClOSER YOU CAN GET TO THE ORGINAl SPOT.