DRG

http://www.goldensoftware.com/newsletter/50/Issue50Sgps5.gif

A Digital Raster Graphic (DRG) map is usually created by the USGS (US Geological Survey). This map shows a proposed hiking trip route. In this map, purple represents the start of the trip and red is the end. The green, yellow and orange show the track at the north end of the map, showing the order of the points.