InterpOSe processes any number of files at the same time, producing a continuous coverage. In OS MasterMap, the entire land surface is covered by a blanket of polygons. Each customer opts to receive polygons in either a 'topological' or an 'independent' format - the result after translation is the same for the initial supply. OS MasterMap does not use tiles, but is supplied in chunks that contain all the features wholly or partly within arbitrary squares. As a result, adjacent chunks contain duplicate features. Features overlapping the edges of chunks are identified and de-duplicated. Each feature is identified by its TOID and version number. These are suitable for associating your own information, and each feature includes comprehensive attribute data.