Product details

Feature types

Feature Type	Identifier Type	Source Product	Description
TopographicArea	TOID	OS MasterMap Topographic Layer	Polygon limited to either a building outline or road surface area.
RoadLink	TOID	OS MasterMap Highways	Section of road from junction to junction.
Road	TOID	OS MasterMap Highways	Collection of RoadLink with a given name.
BLPU (Building Land Parcel Unit)	UPRN (Unique Property Reference Number)	AddressBase Premium	An address location with postal address.
Street	USRN (Unique Street Reference Number)	OS MasterMap Highways	An identifier allocated to a street by a local authority.
ORRoadLink/ ORRoadNode	GUID	Open Roads	Road sections and junctions from our open data product. These features are referred to in OS Open Roads as RoadLink and RoadNode. In this product they are referred to as ORRoadLink and ORRoadNode respectively to distinguish them from the OS MasterMap Highways Networks RoadLink and RoadNode features.

Please refer to the source product documentation for details of each feature that is being related.

Identifier Schemes

Each feature uses a specific identifier scheme for its identifier. These are as follows:

• Unique Property Reference Number (UPRN)

A UPRN is a unique numeric identifier for every address in Great Britain. The identifier is critical and can be found throughout OS's AddressBase products. It provides a complete and consistent

identifier throughout a property’s life cycle. This means the UPRN is assigned to an address at the earliest opportunity and is never reused, even after the property has been demolished.

• Unique Street Reference Number (USRN)

A USRN is a unique and persistent identifier for every street, road, track, path, cycletrack or way in Great Britain and can be found in OS’s Highways Network products and is also a key component in OS’s AddressBase suite of products.

• Topographic Identifier (TOID)

A TOID is a unique identifier, consisting of the letters ‘osgb’ and followed by either thirteen or sixteen digits, associated with every feature in many of Ordnance Survey’s large-scale products. No amends can be made to this code as it may no longer be functional with other OS MasterMap products.

The TOID is based on the Digital National Framework concept and the principles that underpinned it.

These identifiers contain no attribution or information, for example coordinate position. If you need this to visualise your data, we offer a family of Open Identifier products for you to download and freely use under Open Government Licence.

Relationship Source

The following table lists each of the relationships provided and the premium product the relationship has been extracted from.

Correlation Method ID	Source Product for relationship
RoadLink_TOID_TopographicArea_TOID_2	OS MasterMap Highways Networks - Roads
Road_TOID_TopographicArea_TOID_3	OS MasterMap Highways Networks - Roads
Street_USRN_TopographicArea_TOID_4	OS MasterMap Highways Networks - Roads
BLPU_UPRN_TopographicArea_TOID_5	AddressBase Premium
RoadLink_TOID_Road_TOID_7	OS MasterMap Highways Networks - Roads
RoadLink_TOID_Street_USRN_8	OS MasterMap Highways Networks - Roads
BLPU_UPRN_RoadLink_TOID_9	AddressBase Premium
Road_TOID_Street_USRN_10	OS MasterMap Highways Networks - Roads
BLPU_UPRN_Street_USRN_11	AddressBase Premium
ORRoadLink_GUID_RoadLink_TOID_12	OS MasterMap Highways Networks - Roads
ORRoadNode_GUID_RoadLink_TOID_13	OS MasterMap Highways Networks - Roads

Please refer to the OS Open Linked Identifiers Technical Specification for details on how these relationships were extracted and how the original relationships were formed.

General Structure

The Open Linked Identifier data product is supplied in Comma-Separated Value (CSV) format, which comes with Product Version Information files formatted as JavaScript Object Notation (JSON).

Upon downloading the data, you will receive zip files of the eleven Linked Identifier relationships. The generalised naming convention for each Relationship ID is:

{Data Identifier 1}_{Feature Identifier 1}_{Data Identifier 2}_{Feature Identifier 2}_{CorrelationType Number}

For example: BLPU_UPRN_RoadLink_TOID_9

Relationship IDs	Relationship
RoadLink_TOID_TopographicArea_TOID_2	RoadLink <-> TopographicArea
Road_TOID_TopographicArea_TOID_3	Road <-> TopographicArea
Street_USRN_TopographicArea_TOID_4	Street <-> TopographicArea
BLPU_UPRN_TopographicArea_TOID_5	BLPU <-> TopographicArea
RoadLink_TOID_Road_TOID_7	RoadLink <-> Road
RoadLink_TOID_Street_USRN_8	RoadLink <-> Street
BLPU_UPRN_RoadLink_TOID_9	BLPU <-> RoadLink
Road_TOID_Street_USRN_10	Road <-> Street
BLPU_UPRN_Street_USRN_11	BLPU <-> Street
ORRoadLink_GUID_RoadLink_TOID_12	Open Roads RoadLink <-> OSMM Highways RoadLink
ORRoadNode_GUID_RoadLink_TOID_13	Open Roads RoadNode <-> OSMM Highways RoadLink

Comma-Separated Values

Upon downloading the CSV data, you will have 11 zip packages for each relationship. Each zip package contains 4 files, for example BLPU_UPRN_RoadLink_TOID_9.zip extracts:

Four files extracted from BLPU_UPRN_RoadLink_TOID_9.zip

File	Description
BLPU_UPRN_RoadLink_TOID_9.csv	Linked Identifier data (CSV)
BLPU_UPRN_RoadLink_TOID_9_versions.json	Product version information
Licence.txt	OGL Licence
UPRN_RoadLink_TOID_9_202001_description.pdf	Product description

Supply and Update

OS Open Linked Identifiers will be updated through a full supply on a six-weekly basis in line with AddressBase Premium. Each OS Open Linked Identifiers release will follow shortly after the corresponding AddressBase Premium release.

Coverage and File Sizes

The product is released with full Great Britain coverage. As the product has been separated into individual zip files per relationship, each zip file size is dependent on the relationship it holds. The sizes range from a few hundred megabytes to 5-8 giga bytes. Please see the product listing on the OS Data Hub for accurate individual file sizes.