Ordnance Survey - OS MasterMap

OS MasterMap

Ordnance Survey's flagship digital product, launched in November 2001, is OS MasterMap. This is a database that records every fixed feature of Great Britain larger than a few metres in one continuous digital map. Every feature is given a unique TOID (TOpographical IDentifier), a simple identifier that includes no semantic information. Typically each TOID is associated with a polygon that represents the area on the ground that the feature covers, in National Grid coordinates.