FAQ: What is the difference between a theme and a coverage?
What is the difference between a theme and a coverage?
An ArcInfo coverage (GIS dataset) is a physical directory containing files with geographic coordinates that set spatial features. Additionally, a separate INFO directory stores the attribute data associated with the spatial features.
A theme is a structure that exists only within the ArcCAD environment, which integrates data stored in the AutoCAD drawing and GIS datasets.
A theme is defined within an AutoCAD drawing, and this theme references data that is stored in a dBASE file or coverage directory. It is possible to have several themes that point to, or reference, the same coverage (GIS dataset); it is not possible to have one theme point to more than one coverage.
It is not valid to think of a theme as data. A theme is an internal ArcCAD structure by which GIS datasets can be accessed.