# Unique Property Reference Number (UPRN)

The Unique Property Reference Number (UPRN) is the persistent identifier providing consistency across the AddressBase products range.

Each address record has a UPRN, which provides a reference key to join related address records across different datasets.

Throughout its lifecycle, information on the address of a property can change. This may be due to a change of name, change of use, or the eventual demolition of the property. All these changes are reflected against the same UPRN, meaning that users are aware that it is the same physical property.

{% hint style="warning" %}
Please be aware that the UPRN is not the Primary Key for all tables within the [AddressBase Premium](/os-downloads/products/addresses-and-names-portfolio/addressbase-premium.md) and [AddressBase Premium Islands](/os-downloads/products/addresses-and-names-portfolio/addressbase-premium-islands.md) supply. Please see the relational models in [AddressBase Premium structure](/os-downloads/products/addresses-and-names-portfolio/addressbase-premium/addressbase-premium-technical-specification/addressbase-premium-structure.md) and [AddressBase Premium Islands structure](/os-downloads/products/addresses-and-names-portfolio/addressbase-premium-islands/addressbase-premium-islands-technical-specification/addressbase-premium-islands-structure.md) for more information.
{% endhint %}


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