global Configuration parameters specific to the OpenStreetMap (OSM) tile store. Also add 'mbtiles' to "plugins", the store URL to "map.location" and 'osm' to "map.type" for using OSM tile. stores. Edge length of the square tiles received from the server. Maximum available/allowed tile level. OSM servers typically serve map tiles up to level 19. Path of an optional cache directory. If specified, downloaded tiles will we cached to speed up requests and to save network bandwidth. Number of seconds a cached tile is valid. Cache files older than the specified number of seconds are reloaded from the tile server upon request. Use a negative value to indicated an unlimited cache duration.