The Coverage element describes the spatial and temporal characteristics of the object or resource and is the key element for supporting spatial or temporal range searching on document-like objects that are spatially referenced or time referenced. A resource may have both spatial and temporal coverages, or just one of the two, or none. This element may be used in describing resources from many different fields, e.g., archaeology, art, cartography, geography, geographic information systems, medicine, natural sciences, etc. - any field that deals with georeferenced information, spatial data, or time referenced data. Temporal information may also be given in numeric form or in text.
Numbers are preferred.
DC.coverage.hull where the placeName and periodName are qualifiers for textual representation, and the remainder are for coordinate-based classification. The values of the polygon modifier are stored as a single, closed chain of x and y pairs, which may be separated by commas for readability. The hull modifier is required where a complex 3-dimensional extent is required. The values of the hull modifier are stored as a single chain of x, y, z triples, which may be separated by commas for readability. The region of coverage is defined as the convex hull of this set of points.