The national coordinate system is the base of all surveys. To establish uniform national coordinate system and to coordinate the trend of widely application of satellite positioning survey, the Ministry of Interior invited representatives from industries, government, and academics to two seminars and two meetings to discuss and establish the new national coordinate system. The definitions are as follows:
 The new national coordinate system is named as the 1997 Taiwan land base (TWD97). the set up uses the International Terrestrial Reference Frame (abbreviated as ITRF). ITRF is the earth core coordinate system calculated through globe measurement net survey data results. The orientation uses Bureau Internationaldel` Heure (abbreviated BIH) defined at 1984.0 time orientation.
 Reference ellipse body for the new national coordinate system uses 1980 International Union of Geodesy and geophysics (abbreviated as IUGG) published reference ellipse body (GRS80). The parameters for the ellipse are as follows:
long radius a=6378137 m, flat ratio f=1/298.257222101.
 Taiwan, island of Liuqiu, Lu Dao, Lun Tu, and Kwei San island etc. areas projection types uses the horizontal Macartor projection longitude difference 2 degree belt. The central meridian is east longitude 121 degree. The origin of projection is moved west horizontally 250,000 m. The central ratio of meridian scale is 0.9999. The Pang Hu, Kin Men and Machu etc. areas projection types also uses the horizontal Macartor projection longitude difference 2 degree belt. The central meridian is east longitude 119 degree. The origin of projection is moved west horizontally 250,000 m. The central ratio of meridian scale is 0.9999.


