> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-downloads/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/os-downloads/products/transport-network-portfolio/os-open-usrn/os-open-usrn-technical-specification/feature-type/os-open-usrn.md).

# OS Open USRN

## OS Open USRN attributes

The following sub-sections provide details about the attributes included with the single feature type (OS Open USRN) in the product:

### id

A non-persistent integer which is autogenerated and is required within the OGC GeoPackage format.

* Type: Integer
* Multiplicity: \[1]

### usrn

Unique Street Reference Number (USRN), a unique and persistent identifier assigned by the Roads or Highway Authority.

* Type: Integer
* Size: 8
* Multiplicity: \[1]

### street\_type

The type of Street assigned by the Roads or Highway Authority.

{% hint style="info" %}
See the [Street Type values table](/os-downloads/products/transport-network-portfolio/os-open-usrn/os-open-usrn-technical-specification/street-type.md#street-type-values) for allowable values.
{% endhint %}

* Type: Text
* Size: 35
* Multiplicity: \[1]

### geometry

The aggregated geometry of either matched OS Road Links or the Elementary Street Units.

{% hint style="info" %}
For more information, see the [Geometry](/os-downloads/products/transport-network-portfolio/os-open-usrn/os-open-usrn-technical-specification/geometry.md) page.
{% endhint %}

* Type: Geometry (MultiLineString)
* Multiplicity: \[1]


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.os.uk/os-downloads/products/transport-network-portfolio/os-open-usrn/os-open-usrn-technical-specification/feature-type/os-open-usrn.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.