Use for geographic polygons that are the result of layering two or more geographic hierarchies where the polygon being described is the intersect of the layers. For example: State - County - County Subdivision - Place/Remainder - Tract [The portion of a tract that is within a single place (or non-place area) and a single county subdivision] This polygon is made by overlaying the following three geographic hierarchies: 1) State - Place, 2) State - County - Tract, and 3) State - County - Subdivision. The three GeographicLayerBase elements would point to Tract, Place, and County Subdivision.