Extent

A Extent is an instance of gmd:EX_Extent or one of its subclasses.

Its property instances are described below:

Identifier	Title/description	Value domain	Card	Constraint	Specific mapping notes	Guidelines	Example
description [DMF/Core]	Description to identify the extent This is a description of the extent. In case it is implemented as an anchor it can link to a register	String or Anchor	0..1
temporalExtent [DMF/Core]	Temporal Extent This metadata element expresses the temporal extent.	Temporal Extent	0..*	One of temporalExtent, geogId, boundingBox, boundingPolygon or verticalExtent is mandatory	There may be different instances of temporalElement defining the temporal extent of the resource. By default, they are in a single instance of extent, but they may also be in different instances of extent, one of them possibly handling the geographic bounding box. Start and end properties of Temporal Extent are instantiated as TM_Instant. If both are defined, a TM_Period instance links the beginning and ending TM_Instant.
boundingBox [DMF/Core]	Bounding Box This metadata element expresses the spatial extent as a bounding box.	GeographicBox	0..*	One of temporalExtent, geogId, boundingBox, boundingPolygon or verticalExtent is mandatory	Each boundingBox corresponds to a dataset subregion which implies that each boundingBox should be implemented as an instance of the extent property, possibly with the instances of geogId and boundingPolygon corresponding to the same subregion. For similar reasons, each boundingPolygon should be implemented as an instance of the extent property		East: 8.07 West:15.2 North: 57.75 South: 54.56
geogId [DMF/Core]	Geographic Identifier This metadata element expresses the spatial extent as a geographic identifier.	Identifier	0..*	One of temporalExtent, geogId, boundingBox, boundingPolygon or verticalExtent is mandatory	By default, each geogId is implemented as a dedicated extent, but it is acceptable to group many geogId in a single extent possibly with other metadata elements (Integer, boundingPolygon, …)		London or France or postal code
boundingPolygon [DMF/Core]	Bounding Polygon This metadata element expresses the spatial extent as a bounding polygon. Note: if several polygons are needed, then the Extent element (RSEXT) should be repeated. The resource positional extent is intented to provide the extent of the information content. If there is a need to provide extent of the computer file, then the use of the bounding box should be preferred. Regarding nodata: it is possible to have several polygons to indicate holes or void areas. But in DMF, we made the choice to provide this type of information as a coverage quality result	Polygon	0..1	One of temporalExtent, geogId, boundingBox, boundingPolygon or verticalExtent is mandatory	The srsName attribute is instantiated as an XML attribute.
verticalExtent [DMF/Core]	Vertical Extent The lowest and highest vertical extent contained in the dataset. It is expressed in metres.	Vertical Extent	0..1	One of temporalExtent, geogId, boundingBox, boundingPolygon or verticalExtent is mandatory

DMF/Core

DMF/Core defines the minimum set of metadata elements to be implemented by any metadata catalogue. This set satisfies the discovery use case.