Database handle for the object. It is of XML type ID, so is constrained to beunique in the XML document within which it occurs. An external identifier for the object inthe form of a URI may be constructed using standard XML and XPointer methods. This is doneby concatenating the URI for the document, a fragment separator, and the value of the idattribute.
Source
<element name="GroupGroup" substitutionGroup="diggs:AbstractGroup" type="diggs:GroupGroupType"><annotation><appinfo><diggs:deprecated since="3.1.0" note="diggs:groupGroupRef on each member group (diggs:AbstractProjectScopedGroupType)"/></appinfo><documentation>DEPRECATED. Use groupGroupRef on each member group. A feature containing references to a group of groups.</documentation></annotation></element>