Every feature within OS MasterMap has a TOID (TOpographic IDentifier) as the unique reference. This makes it possible to identify any single feature within the dataset with no ambiguity.
Alternative referencing systems can be subject to interpretation between organisations and users, leading to challenges in accurately matching data when exchanging information with others. TOIDs provide a persistent reference throughout a features lifecycle; even if a feature undergoes change the TOID remains the same. This allows customers to link their own data and track change over time.
Having unique references is essential to making the most out of storing data within a national data repository, as these rely on unique referencing to be able to store, sort, manage, query and retrieve data efficiently.