Many geometrical schemes - or map projections - are used to represent the curved surface of the Earth on map sheets. Canada uses the **Universal Transverse Mercator** (UTM) system. It is called transverse because the strips run north-south rather than east-west along the equator. This data class shows a 10 km x 10 km coordinate system based on the UTM projection using the North American Datum 83 (NAD83) grid. It includes: * Military Grid Reference- identifies a specific military grid reference system grid cell * Fire Base Map identifier- five digit identifier used by MNR's Aviation and Forest Fire Management Program to identify a fire basemap * Atlas identifier - identifies a specific grid cell * UTM Map Sheet Number - ID number of a UTM mapsheet This product requires the use of GIS software. [UTM Grid - Map Projections ](http://www.nrcan.gc.ca/earth-sciences/geography-boundary/mapping/topographic-mapping/10733) *[NAD83]: North American Datum 83 *[UTM]: Universal Transverse Mercator