The topological boundary of a TopoSolid consists of a set of directed faces. Note that all faces associated with the TopoSolid, including dangling faces, appear in the boundary. The coboundary of a TopoSolid is empty and hence requires no representation.
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods. This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<complexType name="TopoSolidType"><annotation><documentation>The topological boundary of a TopoSolid consists of a set of directed faces. Note that all faces associated with the TopoSolid, including dangling faces, appear in the boundary. The coboundary of a TopoSolid is empty and hence requires no representation.</documentation></annotation><complexContent><extension base="gml:AbstractTopoPrimitiveType"><sequence><element ref="gml:directedFace" maxOccurs="unbounded"/></sequence></extension></complexContent></complexType>