Preliminary Study on the Classification and Codes of Geodesic Data in WDC-D
MA Jian-hua~(1), SUN Jiu-lin~(1,2) (1.College of Environment and Planning,Henan University, Henan Kaifeng 475001, China; 2.Institute of Geographical Sciences and Natural resources Research,CAS, Beijing 100101, China)
In this paper, the author divides geodesic data into classes with linear classification method firstly. Geodesic data are divided into four levels totally.The quantity of the data in first level is 7, 35 in the second level, 121 in the third level, and 385 in the fourth level. Then the author codes the geodesic data in all levels with the coding method of level code. Every code is composed of eight Arabic numerals and one English alphabet. The one place of the codes from left to right is the letter of "K" that is the sequence code in the WDC- D.The second place of the codes is the one number of " 1 ～ 9" that indicates the first level of the data. The third and the fourth place, the fifth and the sixth place, the seventh and the eighth place of the codes use two number of "00 ～99" to indicate the second, the third and the fourth level of the data respectively. The last place that is the ninth place of the codes uses one number of "1 ～ 3" that indicates the sharing classes of the data. Pablic data use the number of 1, commercisl data use the number of 2, and secret data use the number of 3.