A visualisation of three OS Open TOID features taken from OS MasterMap Topography Layer
OS Open TOID is a comprehensive list of the unique identifiers used in our OS MasterMap data alongside the generalised location of the physical feature. The unique identifier used is the TOID (Topographic Identifier) and is commonly found throughout our data allowing for an easy transition between datasets. It consists of the letters ‘osgb’ followed by either 13 or 16 digits between 0 and 9. In order for the TOID to be effective it is essential that the OS appointed TOID reference is not altered in any way.
The TOID is allocated sequentially when a feature is created by Ordnance Survey and is never reassigned to a different feature. One of the key principles of unique referencing is that the TOID will stay the same throughout the life of a feature. This gives the feature continuity within its life cycle and makes managing change of the product easier.
The product is designed to enable consumers of OpenData that is linked to the TOID to visualise that data in a spatial context. It bridges the gap between the disparate datasets of the OS MasterMap product family and enable the wider adoption of the TOID as a means of a spatial identifier, creating greater linking and sharing data with a spatial context.
This data is usable in a GIS application and can also be integrated into a spatial database.
## Index
* [Product details](/os-downloads/products/buildings-and-infrastructure-portfolio/os-open-toid/os-open-toid-technical-specification/product-details.md)
* [Data structure](/os-downloads/products/buildings-and-infrastructure-portfolio/os-open-toid/os-open-toid-technical-specification/data-structure.md)
* [Product supply](/os-downloads/products/buildings-and-infrastructure-portfolio/os-open-toid/os-open-toid-technical-specification/product-supply.md)
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