A TOID ( TOpographic IDentifier, pronounced ''toyed'') is a unique reference identifier assigned by the

Ordnance Survey Ordnance Survey (OS) is the national mapping agency for Great Britain. The agency's name indicates its original military purpose (see ordnance and surveying), which was to map Scotland in the wake of the Jacobite rising of 1745. There was a ...

to identify every topographical feature in

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It i ...

Topographical identifier

A TOID consists of two parts: a prefix ‘osgb’, and a unique identifier that is 13-16 digits long. For example, the TOID for the

Tower of London The Tower of London, officially His Majesty's Royal Palace and Fortress of the Tower of London, is a historic castle on the north bank of the River Thames in central London. It lies within the London Borough of Tower Hamlets, which is sep ...

is osgb1000006032892. In GML 2, a TOID is encoded as a gml:fid (Feature Identifier); in GML 3 as a gml:id. Around 440 million man-made and natural features have been thus identified: buildings, roads, fields, phone boxes,

pillar box A pillar box is a type of free-standing post box. They are found in the United Kingdom and British overseas territories, and, less commonly, in many members of the Commonwealth of Nations such as Cyprus, India, Gibraltar, Hong Kong, Malta, New Z ...

es, landmarks and many other types. The identification system is designed to be used in GIS, digital

cartography Cartography (; from grc, χάρτης , "papyrus, sheet of paper, map"; and , "write") is the study and practice of making and using maps. Combining science, aesthetics and technique, cartography builds on the premise that reality (or an i ...

and in any customized computer application, including non-cartographic ones, where information about fixed, real-world features needs to be managed. Using consistent identifiers (IDs) makes it much easier to share data between various kinds of applications and systems. A TOID remains constant throughout the lifetime of the real-world feature it identifies, and is guaranteed not to be reassigned to anything else when the feature no longer exists. In OS MasterMap, Ordnance Survey's master database, every fe Wikisature is identified by a TOID. Other attributes of the feature are defined by relating them, via GML, to the TOID. Users of OS MasterMap relate their own data to TOIDs of items of interest to them. Unlike with a custom-designed GIS, one organisation can share data with another organisation easily since TOIDs are maintained centrally by Ordnance Survey, and are free to reuse.

Granularity of TOIDs

Every object in OS MasterMap has its own TOID, including features representing buildings, roads, addresses, and cartographic text. Complex entities such as

Southampton Central railway station Southampton Central railway station is a main line station serving the city of Southampton in Hampshire, southern England. It is on the South West Main Line and also serves the Wessex Main Line and the West Coastway Line. The station is appr ...

, are defined in terms of multiple TOIDs: one for the main building, several others for the platforms, and another for the pedestrian bridge over the tracks. The OS MasterMap Sites Layer has a single TOID for these 'sites'. Similarly, users can create their own "superTOID" that unites features into one entity. This also acknowledges that defining the boundaries of vaguely defined folk objects is subjective: should the station car-park be defined as part of the station, for example? The TOID scheme leaves such decisions to its users, that is, those building information systems for end-users.

TOID revision history

If the data for a feature is edited, for example to reflect a real-life change or to correct an error, then the changes are referenced by TOID. Unless the feature has undergone drastic change, the feature keeps its original TOID, enabling one to track changes to a feature over time if one has access to the historic data.

Intellectual property

In keeping with other OS open data initiatives, Ordnance Survey has a policy on royalty-free use of the TOID with the aim of allowing easier integration of data using its

spatial database A spatial database is a general-purpose database (usually a relational database) that has been enhanced to include spatial data that represents objects defined in a geometric space, along with tools for querying and analyzing such data. Most s ...

: a core part of its vision of a Digital National Framework. "TOID" is a

registered trademark The registered trademark symbol, , is a typographic symbol that provides notice that the preceding word or symbol is a trademark or service mark that has been registered with a national trademark office. A trademark is a symbol, word, or wor ...

of Ordnance Survey.

References

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External links