nad27 nad83 may76 ats77 adindan arc50 australianGeodetic bukitRimpah caa campoInchauspe chuaAstro corregoAlegre djakarta european50 gSegara gSerindung geodetic1949 ghana guam1963 heratNorth hjorsey huTzuShan indian ireland1965 kertau liberia1964 localAstro luzon merchich montjongLowe migeria oldHawaiian osgb psa1956 qornoq sierraLeone1960 tananariveObsv1925 timbalai tokyo voirol wgs60 wgs66 wgs72 wgs84 yacare hermannskogel european79 german italian other
The horizontal adjustment system is the realization of the reference ellipsoid utilizing a particular set of control networks.
nad27: This value refers to an adjustment completed in 1932 of first order triangulation done in North America prior to 1927. Associated geodetic calculations were based on the Clarke 1866 ellipsoid.
nad83: This refers to a conventional terrestrial system (geocentric) realized by modifying the US Navy Navigation Satellite System (Doppler) reference frame (NSWC 9Z-2). Classical terrestrial network observations and space system data for North America were adjusted togther in July 1986, to create the nad83 system.
may76: This is a readjustment of nad27 based on the Clarke 1866 ellipsoid completed in 1976. This adjustment is used mainly in Ontario.
ats77: Refers to the Average Terrestrial System 1977, which is used primarily in the Maritime provinces of Canada.
caa: Refers to Camp Area Astro.
wgs60: Refers to World Geodetic System 1960.
wgs66: Refers to World Geodetic System 1966.
wgs72: Refers to World Geodetic System 1972.
wgs84: Refers to World Geodetic System 1984.
osgb: Refers to Ordnance Survey of Great Britain.
psa1956: Refers to Provisional South American 1956.
other: Allows the specification of another horizontal adjustment system.