Use this command to measure the geodetic distance between points in your map.
The geodetic distance is the actual distance along the ground, taking into account the curvature of the Earth. For example, if you have a Mercator map of the world, use this command to measure how many miles wide Greenland is.
This command is different from the DIST command, which measures the simple Pythagorean distance between two points, not the underlying physical distance. Map distortion (due to the coordinate system), makes the actual distance on the ground considerably different from the distance on the surface of the map.