Related Components

What are related components?

Related components provide supplementary non-geospatial information or context about addresses. They can be linked to an address record in a feature type using the Unique Property Reference Number (UPRN) as the foreign key.

There are three related components in the OS NGD:

• Alternate Address: These provide alternative address labels where they exist for the ‘current’ address represented on a given feature type.

• Other Classification: These provide additional Valuation Office Agency (VOA) classification information.

• Related Entity: These contain cross-reference relationship information between addresses and features in other OS NGD themes (such as buildings, sites, roads and boundaries) or third-party data sets.

The OS NGD Address Theme data structure diagram below is applicable to the latest data schema versions of all address feature types (i.e. data schema version 3.0 of Built Address, Historic Address, Non-Addressable Object and Pre-Build Address, and data schema version 1.0 of Royal Mail Address and Street Address):

OS NGD Address Theme data structure diagram showing the theme name, collection names, feature type names, and related component names.

Postal Address Related Component

• Until September 2025, Postal Address Related Component was the fourth related component in the OS NGD. It has been discontinued in the latest data schema version 3.0 of the Built Address, Historic Address, Non-Addressable Object and Pre-Build Address Feature Types in the GB Address and Islands Address Collections, which released in September 2025.

• The Postal Address Related Component contained delivery point data from the Royal Mail Postcode Address File (PAF). This information is now available in the new Royal Mail Address Feature Type (which launched in September 2025), which can be found in the GB Address and Islands Address Collections.

• The Postal Address Related Component is still provided against the older (maintenance) data schema versions 1.0 and 2.0 of the Built Address, Historic Address, Non-Addressable Object and Pre-Build Address Feature Types in the GB Address and Islands Address Collections. These data schema versions are available for customers to use, but they are now older and in maintenance mode. (Data schema version 3.0 is the latest and recommended data schema version to use for these feature types.)

When will related components be provided?

Related components will always be provided if you have chosen to receive any of the four following feature types from the OS NGD Address Theme: Built Address, Historic Address, Non-Addressable Object or Pre-Build Address. The primary identifier for these four feature types is the URPN (Unique Property Reference Number).

Related components will not be provided for the Royal Mail Address or Street Address Feature Types as their primary identifiers are Royal Mail's Unique Delivery Point Reference Number (UDPRN) and Unique Street Reference Number (USRN), respectively, not UPRN.

How to handle related components

The related components do not contain geometry and therefore need to be joined to the relevant feature type table using the UPRN. When data is supplied, you will receive related component data split out by feature type.

For example, customers taking data schema version 3.0 of the Pre-Build Address Feature Type in GeoPackage format will receive:

• Feature type: Pre-Build Address

• Related component: Pre-Build Alternate Address

• Related component: Pre-Build Related Entity

• Related component: Pre-Build Other Classification