for measuring the coordinates of an unknown point, the instrument should know the coordinates of the point on which it is setup and the instrument should also know our reference coordinate directions (i-e which direction corresponds to Northing/Easting), tundmatu punkti koordinaatide mõõtmiseks peaks mõõtevahend teadma selle punkti koordinaate, millele on mõõtevahend seadistatud, ja tundmatu punkti koordinaatide suundi