a widely used example is the tmc standard for location-code tables for referencing traffic data. tmc, which stands for traffic message channel, is part of the radio data system (rds), which is implemented as a sub-carrier modulation of a commercial fm broadcast signal. the tmc tables primarily provide references to point locations along major roads corresponding to intersections with other roads. a table entry identifies a point location using both contextual information (such as, region, road and section of road, name of intersection) and approximate longitude/latitude coordinates.