Coordinate systems Numeric methods of representing locations on the earth's surface. Relating map data to coordinate systems ensures accuracy when entering data from different sources. Corridor A map region or area of user-specified width drawn around one or more map features. Related term buffer. Coverage A digital analog of a single map sheet having one theme such as roads, soils, streams, vegetation, elevation, etc.
Data dictionary A coded catalog of all data types listing data names and structures.
A digital file consisting of a set of records containing data from a user-defined domain. Each record contains fields having a specific structure. A tablet or board-like device for converting analog electric signals of an absolute or relative position on the tablet surface to digital x,y coordinates. This process yields vector data consisting of points, lines, and polygons that will need to be edited. The resolution, or density of wires in the grid, vary from 1,000 to 10,000 lines per inch.