a procedure used to measure horizontal and vertical distances on a planimetric map —note 1. a common coordinate system is used to spatially register geographic data for the same area —note 2. a coordinate system is usually defined by a map projection, a spheroid of reference, a datum, one or more standard parallels, a central meridian, and possible shifts in the x- and y-directions to locate x,y positions of point, line, and area features This definition last updated 07/28/2008