# OS Open USRN Technical Specification

## Product overview

OS Open USRN is an open dataset of all Unique Street Reference Numbers (USRNs) within [OS MasterMap Highways Network](/os-downloads/products/transport-network-portfolio/os-mastermap-highways-network-fundamentals.md), with an associated simplified line geometry representing the geographic extent of each USRN.

{% hint style="info" %}
A USRN is a unique and persistent identifier for a street contained in either the National or Scottish Street Gazetteer. Every street, road, track, path, cycle track or way is assigned a USRN by a Roads Authority, Local Highway Authority or Highways England.
{% endhint %}

This product has been designed to enable users to easily share information held against a USRN with a location and to link together information associated with USRNs, enabling location-specific visualisation and analysis.

<figure><img src="/files/2jGrmeYuOsmb4EZaW161" alt="A visualisation of the OS Open USRN dataset showing individual streets highlighted."><figcaption><p>A representation of OS Open USRN data against a background map.</p></figcaption></figure>

## Product structure <a href="#bookmark4" id="bookmark4"></a>

OS Open USRN is a vector dataset with a single line feature for each USRN. Each of these features will have accompanying attribution and a simplified line geometry.

The following pages will detail the attribution held against the features in this dataset and provide further information about the source and simplification of the geometry.

## Index <a href="#bookmark5" id="bookmark5"></a>

This technical specification includes the following sections:

* [Street Type](/os-downloads/products/transport-network-portfolio/os-open-usrn/os-open-usrn-technical-specification/street-type.md)
* [Feature type](/os-downloads/products/transport-network-portfolio/os-open-usrn/os-open-usrn-technical-specification/feature-type.md)
* [Geometry](/os-downloads/products/transport-network-portfolio/os-open-usrn/os-open-usrn-technical-specification/geometry.md)
* [Metadata](/os-downloads/products/transport-network-portfolio/os-open-usrn/os-open-usrn-technical-specification/metadata.md)

{% hint style="info" %}
The [OS Open USRN Overview](/os-downloads/products/transport-network-portfolio/os-open-usrn/os-open-usrn-overview.md) details what coordinate reference system is used by OS Open USRN and gives product supply information (including the available format, supply mechanism, coverage and currency).
{% endhint %}


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