> 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/addresses-and-names-portfolio/os-emergency-services-gazetteer/os-esg-technical-specification.md).

# OS ESG Technical Specification

This technical specification provides detailed technical information about the OS ESG. It is targeted at technical users and software developers.

## Product overview

The OS Emergency Services Gazetteer (OS ESG) is a product that offers a national view for Great Britain (i.e. England, Wales and Scotland). The product was designed to support the Emergency Services with incident response, incident reporting and situational awareness by providing pivotal features such as road and motorway junctions.

The OS ESG is structured as a series of relational tables:

* [Basic Land and Property Unit (BLPU)](/os-downloads/products/addresses-and-names-portfolio/os-emergency-services-gazetteer/os-esg-technical-specification/feature-type/blpu-type-21-record.md), which shows fixed locations
* [Local Property Identifier (LPI)](/os-downloads/products/addresses-and-names-portfolio/os-emergency-services-gazetteer/os-esg-technical-specification/structured-data-types/lpi-type-24-record.md), which identifies the BLPUs
* [Classification](/os-downloads/products/addresses-and-names-portfolio/os-emergency-services-gazetteer/os-esg-technical-specification/code-lists/classificationcode.md), which provides feature codes

<figure><img src="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2FStOu8iP6hGDVWg9DYfK8%2F05%20-%20Parent%20Child%20uprn%20bridge%20interaction%201080%20x%201080.png?alt=media&amp;token=45806010-f79a-4e61-bbf0-585b45c7e2eb" alt="Example image showing bridge interactions data in the OS Emergency Services Gazetteer. A background map has been included to provide context."><figcaption><p>Example image showing bridge interactions data in the OS Emergency Services Gazetteer. A background map has been included to provide context.</p></figcaption></figure>

<figure><img src="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2FcazirJ22YXLcOrZGKM5g%2FParent%20Child%20uprn%20tunnel%20interaction%201x1.png?alt=media&amp;token=ed2210f6-5e10-47c7-b253-0c26ca76f615" alt="Example image showing tunnel interactions data in the OS Emergency Services Gazetteer. A background map has been included to provide context."><figcaption><p>Example image showing tunnel interactions data in the OS Emergency Services Gazetteer. A background map has been included to provide context.</p></figcaption></figure>

## **Index**

This technical specification includes the following sections:

* [Feature type](/os-downloads/products/addresses-and-names-portfolio/os-emergency-services-gazetteer/os-esg-technical-specification/feature-type.md)
* [Structured data types](/os-downloads/products/addresses-and-names-portfolio/os-emergency-services-gazetteer/os-esg-technical-specification/structured-data-types.md)
* [Code lists](/os-downloads/products/addresses-and-names-portfolio/os-emergency-services-gazetteer/os-esg-technical-specification/code-lists.md)
* [Dataset metadata](/os-downloads/products/addresses-and-names-portfolio/os-emergency-services-gazetteer/os-esg-technical-specification/dataset-metadata.md)


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