A reference from a project-scoped group to another project-scoped group it is itselfa member of: group nesting, stated in the member-cites-group direction. It is namedfor its class, as is every member of this family: the base type of each featureclass carries a reference named for that class (diggs:samplingFeatureGroupRef,diggs:sampleGroupRef, diggs:measurementGroupRef, diggs:observationGroupRef anddiggs:projectGroupRef), and this one sits on the group base type itself. Its targetis diggs:AbstractProjectScopedGroup, with no separate head for a group of groups,because a group of groups is itself a group. Not diggs:groupRef, a released elementmeaning the reverse, a group pointing down at its member groups, held bydiggs:GroupGroupType; the two are not interchangeable. Targeting the project-scopedhead also means a group of this kind never nests inside a deprecated one. Given byreference 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="groupGroupRef" type="diggs:FeatureReferenceType"><annotation><appinfo source="urn:x-gml:targetElement">diggs:AbstractProjectScopedGroup</appinfo><documentation>A reference from a project-scoped group to another project-scoped group it is itself a member of: group nesting, stated in the member-cites-group direction. It is named for its class, as is every member of this family: the base type of each feature class carries a reference named for that class (diggs:samplingFeatureGroupRef, diggs:sampleGroupRef, diggs:measurementGroupRef, diggs:observationGroupRef and diggs:projectGroupRef), and this one sits on the group base type itself. Its target is diggs:AbstractProjectScopedGroup, with no separate head for a group of groups, because a group of groups is itself a group. Not diggs:groupRef, a released element meaning the reverse, a group pointing down at its member groups, held by diggs:GroupGroupType; the two are not interchangeable. Targeting the project-scoped head also means a group of this kind never nests inside a deprecated one. Given by reference only.</documentation></annotation></element>
