a map database represents a road network along with associated features. map providers can choose various models of a road network as a basis to formulate a database. commonly, such a model comprises basic elements (nodes, links and areas) of the road network and properties of those elements (location coordinates, shape, addresses, road class, speed range, etc.). the basic elements are referred to as features and the properties as attributes. other information associated with the road network is also included, including points of interest, building shapes, and political boundaries. this is shown schematically in the adjacent image. geographic data files (gdf) is a standardized description of such a model.