Abbeviated as "CM". Abbreviation for "Central Meridian". EPSG guidance note number 7. 2002-06-22 false The longitude of the point from which the values of both the geographical coordinates on the ellipsoid and the grid coordinates on the projection are deemed to increment or decrement for computational purposes. Alternatively it may be considered as the longitude of the point which in the absence of application of false coordinates has grid coordinates of (0,0). Sometimes known as "central meridian (CM)". urn:ogc:def:parameter:EPSG::8802 Longitude of natural origin