The World Geodetic System defines a reference frame for the earth, for use in geodesy and navigation. The latest revision is WGS 84 dating from 1984 (last revised in 2004), which will be valid up to about 2010. Earlier schemes included WGS 72, WGS 66, and WGS 60. History Efforts to supplement the various national surveying systems began in the 19th century with F.R. Helmert's famous books (Mathematical and Physical Theory of Physical Geodesy). Austria and Germany initiated the foundation of a… (More on Wgs84)