Area - a closed figure bounded by lines. Base map - a map containing geographic features used for locational reference. The code used by most civilian GPS receivers. Coordinate - an x,y location in a Cartesian coordinate system or an x,y,z location in a three dimensional matrix.
Coordinates represent locations in relation to other locations.
Coordinate system - a system used to measure horizontal and vertical distances on a map. Data in GIS databases are assigned locations based on this system. Coverage - a collection of associated thematic maps represented as one digital map. DEM - Digital Elevation Model data. A database of elevation data represented by a regularly-spaced set of x,y,z locations.