The GB Codes of China database is a comprehensive index of the GB (Guo Biao, or National Standard) codings for administrative units of China down to the county level. The codes provide a dynamic matrix for the identification of spatially- and temporally-specific data on administrative units. The codes are fundamental to the CITAS mission of promoting the intercomparability of Chinese data through the provision of geocoding standards. At this writing (January 1996), the database covers the period 1982-1994. Future versions will extend the coding backward and forward in time. Virtually all of the GB codes were derived from official codings published by the Chinese National Bureau of Standards. In rare cases in which official codes do not exist, codes have been assigned and noted.
Because each coding is given a "from" and "to" date, the database provides a continuous, dynamic coverage of administrative codings for any date from January 1, 1982 to December 31, 1994. Thus, users with spatial data that pertain to a specific date can derive a set of spatial codes for that date. The database also contains basic information about the status of the unit specific to time, including the name, the administrative status of the prefecture in which a county-level unit is located, the administrative status of the county-level unit itself, and a coding for the type of change or changes that brought the unit into its current status. This information provides a continuous administrative history of each unit, and permits the reconstruction of China's administrative units on any date. The GB Code database is keyed to digital map coverages of administrative boundaries. Currently there are three basic coverages (1982, 1996, and 1990, along with variants). At a later stage, map coverage will also be continuous so that codings and corresponding coverages will be available for any date. The ultimate goal is the automated comparison of data at different points in time. The design of this system, and the role of the GB Codes of China database, is described in the document Construction of the County Boundary Database.
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