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The GeographicDescription is required to give gives a clear, textual description of the data set's geographical extent. It can be seen as an summary of the GeographicalBoundingBox or BoundingPolygon for operational experts.
The inclusion of a bounding box or polygon is a good practice in the GIS world. They are useful for applications that represent the data graphically, to set the initial window size. They are also facilitate the evaluation of the geographical coverage of a data set without having to parse and decode the full data set.
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