Longitude (LONG)
Longitude is generally defined as "the angle between the plane of a given meridian and an arbitrary initial meridian, generally the meridian of Greenwich" (ACSM, 1978, page 97). As with latitude, longitude can be astronomic, geocentric or geodetic. Geodetic longitude, "the angle between the plane of a geodetic meridian and the plane of an initial meridian" (ACSM, 1978, page 98), is used in this attribute. In the United States geodetic longitudes are numbered from the Meridian of Greenwich, and in the North American Datum 1927, are computed from the meridian of Meades Ranch.
1995
