OS Open Linked Identifiers Overview

This overview introduces OS Open Linked Identifiers & gives context for all users – highlighting key features, giving examples of potential uses, & listing details on file sizes, supply formats, etc.

OS Open Linked Identifiers is a dataset containing the authoritative relationships between Unique Property Reference Numbers (UPRNs), Unique Street Reference Numbers (USRNs) and Topographic Identifiers (TOIDs).

These relationships have been extracted from the AddressBase Premium and OS MasterMap Highways Networks products. The Product aims to provide all the valuable relationships between addresses, roads and OS MasterMap features.

The following diagram and table show all the feature types that we have included such as address records, building outlines, road surface area, road names, road sections and street records, and the relationships between them that we provide links for.

OS Open Linked Identifiers graph showing the relationship between TOIDs, UPRN, USRNs, and GUID

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.

The product consists of 11 relationships as shown in the diagram above. Each relationship is available to download individually from the OS Data Hub. These relationships support a number of data processing workflows and specific use cases for each are listed in Uses of OS Open Linked Identifiers.

The product is supplied in the form of join tables in the CSV file format and is intended to be loaded into database products. Please see the OS Open Linked Identifiers - Getting Started Guide for details on how to import the join tables into a database.

Once the relationship table has been imported into a database it can be used to join two dataset tables each using different identifiers. For example, if you had data that listed properties which used the Unique Property Reference Number (UPRN) as its primary key, and you also had data related to the streets which used the Unique Street Reference Number (USRN), then you could join these data tables allowing you to lookup information about the street that a property is on. This is just an example for one of the eleven tables. Each table has specific use cases depending on the feature tables that are being linked.

These relationships have been extracted from our premium data products and provided in OS Open Linked Identifiers under open license to enable more public data to be linked together.

This is purely a data product which provides the identifiers being joined with version information to enable reliable data linking. There is no geometry provided in this product. Each relationship file provides full coverage for Great Britain. The product is intended for use with a database only as the lack of spatial information (spatial indexes) and large files make it unsuitable for use in GIS packages.

Unique Property Reference Number (UPRN)

A UPRN is a unique numeric identifier for every addressable location in Great Britain. The identifier is critical for property related information and can be found throughout OS's AddressBase products. An addressable location may be any kind of building, residential or commercial, or it may be an object that might not have a ‘normal’ address – such as a bus shelter or an electricity substation. UPRNs provide these addressable locations with a consistent, persistent identifier never being reused.

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. It can be found in the OS MasterMap 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 issued by Ordnance Survey, consisting of the letters ‘osgb’ and followed by up either thirteen or sixteen digits, associated with every feature in many of Ordnance Survey’s large-scale products. For this to be functional across all OS MasterMap products, this must never be altered or changed.

The TOID is based upon the Digital National Framework concept and the principles that underpin it.

Key features

The Correlation Method ID is a unique identifier for a specific relationship between the featureTypes. The generalised naming convention for each Correlation Method ID is:

{Feature Type 1}_{Identifier Scheme 1}_{Feature Type 2}_{Identifier Scheme 2}_{Correlation Method Number}

This means you can easily identify the feature tables and related identifier schemes which are being linked together by each relationship. The correlation method number is also unique to each relationship.

For example, the Correlation Method ID “RoadLink_TOID_TopographicArea_TOID_2” references:

• Identifier 1:

  • Feature Type: RoadLink

  • Identifier scheme: TOID

• Identifier 2:

  • Feature Type: TopographicArea

  • Identifier scheme: TOID

• Correlation Method Number: 2

With each identifier we have provided associated version information to enable reliable linking to your data. This version information is extracted from the most recent release of the premium product the feature type has been extracted from.

A Confidence Value is assigned to each identifier pairing to indicate the reliability of the version information provided in this product in relation to the version of the features used to form the correlation in the original product. The Confidence Value is given for each relationship, which is defined as:

Confidence Value	Definition
Version information is correct	The version information provided is the same as the version of the feature used to create the correlation.
Version information has potentially changed	The version information could be different from the version of the feature that was used to create the correlation.
Version information has changed	The version information provided is different from the version of the feature used to create the correlation.

Knowing that the feature might have been updated since a relationship was formed helps identify where a relationship may no longer be valid.