A map distribution server that comprises a communication device and is connectable to a navigation device and adapted to distribute map data via the communication device to the navigation device, comprising: a map update data management table comprising map update data IDs, and for each of the IDs a version indicating when the map update data designated by the ID was generated, a path to said map update data and a dependency map updating data ID as a map update data ID designating previous map update data on which the map update data depends, wherein said map update data is a set of difference update data, which indicates the differences between a past and a later map and includes processing instructions; a memory adapted to store a per-area map update data management table holding an area ID to specify an area of said map data, a version of said specified area, and for each version of said specified area a list of necessary map update data IDs; a map update data manager adapted to refer to said per-area map update data management table and to select a map update data ID required for updating a specific area selected based on an input from said navigation device to its latest version; and a map update data distributor adapted to distribute map update data corresponding to said selected map update data ID via the communication device to the navigation device; wherein the map update data management table is further adapted to comprise for each map update data ID a dependency map updating data ID as a map update data ID designating previous map update data on which the map update data depends; the map update data manager is further adapted to obtain any dependency map updating data IDs associated with the map update data IDs (1403, 1201) to be updated from the per-area map update data management table; and the map update data distributor is further adapted to distribute also map update data corresponding to the obtained dependency map updating data IDs via the communication device to the navigation device. a map update data management table comprising map update data IDs, and for each of the IDs a version indicating when the map update data designated by the ID was generated, a path to said map update data and a dependency map updating data ID as a map update data ID designating previous map update data on which the map update data depends, wherein said map update data is a set of difference update data, which indicates the differences between a past and a later map and includes processing instructions; a memory adapted to store a per-area map update data management table holding an area ID to specify an area of said map data, a version of said specified area, and for each version of said specified area a list of necessary map update data IDs; a map update data manager adapted to refer to said per-area map update data management table and to select a map update data ID required for updating a specific area selected based on an input from said navigation device to its latest version; and a map update data distributor adapted to distribute map update data corresponding to said selected map update data ID via the communication device to the navigation device; wherein the map update data management table is further adapted to comprise for each map update data ID a dependency map updating data ID as a map update data ID designating previous map update data on which the map update data depends; the map update data manager is further adapted to obtain any dependency map updating data IDs associated with the map update data IDs (1403, 1201) to be updated from the per-area map update data management table; and the map update data distributor is further adapted to distribute also map update data corresponding to the obtained dependency map updating data IDs via the communication device to the navigation device.