A GridCoverage is a discrete point coverage in which the domain is a geometric grid of points encoded using gml:Grid (not its subtypes gml:RectifiedGrid or a subtype of AbstractReferenceableGrid). Note that this is similar to the MultiPointCoverage except that a gml:Grid shall be used to describe the domain.<br/>In order to address ambiguities in the gml:Grid definition, this GML Application Schema for Coverages imposes additional constraints on the use of a gml:Grid within a gmlcov:GridCoverage. (Specifically, there is no provision in the definition of gml:Grid definition to express the relationship between the grid positions and this geometry's coordinate reference system, which will always exist in some contexts, such as a Web Coverage Service. This coordinate reference system will be explicitly referenced in the srsName attribute of the gml:SRSReferenceGroup of gml:Grid, or be inherited from an enclosing container element, such as the gml:Envelope of this gmlcov:GridCoverage.) Since provision for expressing a relationship does not exist, whenever used in gmlcov:GridCoverage, the relationship shall be simple. In this simple relationship, the dimension attribute of the gml:Grid shall be identical to the dimension of the geometry's coordinate system, the axes of the gml:Grid shall be identical to the axes of the geometry's coordinate system (which requires that the axisLabels be identical to those in the coordinate system definition), and the limits shall be treated as being expressed as coordinates in the geometry's coordinate reference system.<br/>Clearly these additional constraints are quite limiting, in that gridded datasets whose Reference points happen to exist exactly at integral coordinates of a spatial coordinate system at a spacing of exactly one in all coordinate dimensions are exceedingly rare, unless that coordinate system is part of a gml:ImageCRS. Nevertheless, the gmlcov:GridCoverage is available for such purposes.<br/>It is recommended that the more sensible provisions of the gmlcov:RectifiedGridCoverage or gmlcov:ReferenceableGridCoverage be utilized for all gridded datasets, since their domains can accommodate the simple provisions of the gmlcov:GridCoverage as well as more complex referencing situations. <br/>