Longitude

Because the Transverse Mercator projection is very accurate in narrow zones, it has become the basis for a global coordinate system called the Universal Transverse Mercator System or UTM System. The globe is subdivided into narrow longitude zones, which are projected onto a Transverse Mercator projection. A grid is constructed on the projection, and used to locate points. The upside of the grid system is that, since the grid is rectangular and decimal, it is far easier to use than latitude and longitude. The downside is that, unlike latitude and longitude, there is no way to determine grid locations independently.