The National Topographic System of Canada Topographic maps produced by Natural Resources Canada conform to the National Topographic System (NTS) of Canada. The National Topographic System provides general-purpose topographic map coverage of the entire Canadian landmass. These maps depict, in detail, ground relief, drainage, forest cover, administrative areas, populated areas, transportation routes and facilities, and cultural features. They are available in two standard scales, 1/50 000 and 1/250 000. The maps show a geographic grid (longitude and latitude) and a Universal Transverse Mercator (UTM) grid (kilometres). The area covered by a given map sheet is determined by its latitude and longitude. Since the National Topographic System uses a standard numbering system, knowing the map number allows you to quickly identify adjacent map sheets. The 1/250 000 scale maps (1 cm equals 2.5 km) are identified by a combination of numbers and letters, from A through P (e.g. 12A, below in yellow). The 1/250 000 blocks are further sub-divided into sixteen segments (1 to 16), forming blocks used for 1/50 000 scale mapping (1 cm equals 0.5 km).