A reference to the ground model a design was prepared from: the observation system,typically a diggs:GeoUnitSystem, whose observations carry the units and propertiesthe design assumed. It is a reference, not a contained object: a ground model isalready a feature with its own anchoring sampling feature and observation semantics,and a copy inside a basis would create a second place for the two to disagree.Repeatable, because one scope can have several ground models distinguished bygeoUnitType as well as by extent, for example a soil model, a rock model and a modelof parameters assigned per borehole. Models that describe different parts of aprogram belong on separate bases, each with its own scope, chained to a program-widebasis through basedOnRef, so that a design citing one basis resolves exactly themodel that governs it. Given by reference only.
The gml:identifier value of the referenced feature, as a fully qualifiedvalue. It gives an alternative to the gml:id in xlink:href for findingthe referenced feature, mainly to reference a feature by a globallyunique identifier and where naming conflicts occur with gml:id whenaccessing data in external files.
<element name="groundModelRef" type="diggs:FeatureReferenceType"><annotation><appinfo source="urn:x-gml:targetElement">diggs:AbstractObservationSystem</appinfo><documentation>A reference to the ground model a design was prepared from: the observation system, typically a diggs:GeoUnitSystem, whose observations carry the units and properties the design assumed. It is a reference, not a contained object: a ground model is already a feature with its own anchoring sampling feature and observation semantics, and a copy inside a basis would create a second place for the two to disagree. Repeatable, because one scope can have several ground models distinguished by geoUnitType as well as by extent, for example a soil model, a rock model and a model of parameters assigned per borehole. Models that describe different parts of a program belong on separate bases, each with its own scope, chained to a program-wide basis through basedOnRef, so that a design citing one basis resolves exactly the model that governs it. Given by reference only.</documentation></annotation></element>
