> 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/areas-and-zones-portfolio/code-point-open/code-point-open-overview.md).

# Code-Point Open Overview

This overview introduces Code-Point Open, giving context for all users – highlighting key features, providing examples of uses, and listing details such as file sizes, supply formats, etc.

Code-Point Open locates over 1.7 million postcode units for Great Britain, each having a notional geographical location. Postcodes are an alphanumeric abbreviated form of an address. Postcode units are unique references and identify an average of 15 addresses. In some cases, where an address receives a substantial amount of mail, a postcode will apply to only one address and is defined as a large-user postcode. The maximum number of addresses in a postcode is 100.

## Key product features <a href="#bookmark1" id="bookmark1"></a>

With each coordinate point, the Code-Point Open product provides:

* A postcode
* A positional quality indicator (PQI), which indicates the quality of the data underlying the Code-Point location coordinate (CPLC)
* The country code (either England, Scotland or Wales)
* The National Health Service (NHS) region and area codes
* The local government county, district and ward codes

## Product applications <a href="#bookmark2" id="bookmark2"></a>

Code-Point Open can be used to display and analyse any data collected at the postcode level. This has led to the product being widely used in a variety of applications, including the following:

* Site location
* Enabling web searches
* Market analysis and profiling
* Health and epidemiology
* Resource allocation
* End-to-end journey route planning
* Socio-economic profiling
* Sales targeting

## Index

This overview includes the following sections:

* [Product details](/os-downloads/products/areas-and-zones-portfolio/code-point-open/code-point-open-overview/product-details.md)
* [Product supply](/os-downloads/products/areas-and-zones-portfolio/code-point-open/code-point-open-overview/product-supply.md)


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