identifiers assigned to entries in a table are 16-bit integers and therefore have a range of 65536 values. this is too few to cover the world, so separate tables are formulated for each country or region of a country. for a given metropolitan region, only intersections along freeways, arterials and some major roads are included. this is illustrated in the following figure for the detroit metro area. the coverage is intended for providing traffic advisory information on high-use roads. traffic-based route planning, on the other hand, requires coverage of all or almost all major roads and, therefore, is not adequately supported by tmc location code tables as they are currently formulated.