Because this database is not complete for the World, there is no specific tiling structure. However, North America and Europe are in a tiled layout due to their large area. Several of the areas do not cover an entire country. This is a historical phenomenon. These areas were captured purely for publishing needs and they often have small areas of data from neighbouring countries.
All areas have international and first order divisions.
Some areas also have second order admin divisions. All of these polygons have identifiers, showing which admin division they are.