Coordinate reference system

The coordinate reference system used by OS MasterMap Highways Network is the British National Grid. The British National Grid (BNG) spatial reference system uses the OSGB36 geodetic datum and a single Transverse Mercator projection for the whole of Great Britain. Positions on this projection are described using easting and northing coordinates in units of metres. The BNG is a horizontal spatial reference system only; it does not include a vertical (height) reference system.

In the Geography Markup Language (GML) data, this is represented by reference to its entry in the EPSG registry, as http://www.opengis.net/def/crs/EPSG/0/27700.