Administrative areas may be arranged hierarchically. Partitions that represent a location in the hierarchy are named using relevant identifiers using the following scheme:
Currently, layers using this scheme are partitioned at one of two levels in the hierarchy.
- Country level. This is always the root of the administrative hierarchy.
- Clip level. The clip level depends on the country and is the level at which administrative polygons are guaranteed to form a polygonal partition (spanning, non-overlapping) with consistent segment-level admin coding. The clip level is the first (minimum) level for which the boundaries are polygonal and span. For example, clip-level in the United States is admin level 3 (county). In Germany, it is also level 3 (Kreis).
A layer may contain both country partitions and clip-level admin partitions.