Derived at 6 stations. Accuracy 3m, 3m and 4m in X, Y and Z axes. Also used as a transformation from SAD69 to SIRGAS-Chile - see code 6970. Unlike IGM Chile, NGA extends use of this tfm to all Chile south of 44°S.
U.S. National Geospatial Intelligence Agency (NGA) Standard 0036 v1.0.0 of 2014-07-08.
See CRS code 4618 for recommended coordinate axis representation for the human interface.