> 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/addressbase-plus/addressbase-plus-technical-specification.md). # AddressBase Plus Technical Specification AddressBase Plus contains current properties including addresses sourced from local authorities, Ordnance Survey and Royal Mail, all provided with a Unique Property Reference Number (UPRN). It has more records than AddressBase as it includes objects without postal addresses and live records captured by Local Authorities but not matched to Royal Mail PAF data. The product enables the end-user to locate an address or property on a map using either X, Y coordinates supplied on a British National Grid or Latitude and Longitude coordinates provided on an ETRS89 projection. The product also includes cross references to OS MasterMap products via OS MasterMap Topography Layer and OS MasterMap Highways Network Layer TOID references. This technical specification includes the following sections: * [Data formats](/os-downloads/products/addresses-and-names-portfolio/addressbase-plus/addressbase-plus-technical-specification/data-formats.md) * [Supply and update](/os-downloads/products/addresses-and-names-portfolio/addressbase-plus/addressbase-plus-technical-specification/supply-and-update.md) * [AddressBase Plus structure](/os-downloads/products/addresses-and-names-portfolio/addressbase-plus/addressbase-plus-technical-specification/addressbase-plus-structure.md) * [Feature types](/os-downloads/products/addresses-and-names-portfolio/addressbase-plus/addressbase-plus-technical-specification/feature-types.md) * [Code lists and enumerations](/os-downloads/products/addresses-and-names-portfolio/addressbase-plus/addressbase-plus-technical-specification/code-lists-and-enumerations.md) * [CSV to GML mapping](/os-downloads/products/addresses-and-names-portfolio/addressbase-plus/addressbase-plus-technical-specification/csv-to-gml-mapping.md) * [Example records](/os-downloads/products/addresses-and-names-portfolio/addressbase-plus/addressbase-plus-technical-specification/example-records.md) Additional documentation covering the complete family of AddressBase products is available in the AddressBase Fundamentals pages. These covers key elements of design for AddressBase products, including: * [Future and past publication dates](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/future-and-past-publication-dates.md) * [Unique Property Reference Number (UPRN)](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/unique-property-reference-number-uprn.md) * [Coordinate reference systems](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/coordinate-reference-systems.md) * [Classification scheme](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/classification-scheme.md) * [Data sources](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/data-sources.md) * [Street names and numbering](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/street-names-and-numbering.md) * [Currency completeness and precision](/os-downloads/products/addresses-and-names-portfolio/addressbase-core/addressbase-core-overview/currency-completeness-and-precision.md) * [Product supply](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/product-supply.md) * [AddressBase local custodian codes](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/addressbase-local-custodian-codes.md) * [AddressBase Islands local custodian codes](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/addressbase-islands-local-custodian-codes.md) --- # 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: ``` GET https://docs.os.uk/os-downloads/products/addresses-and-names-portfolio/addressbase-plus/addressbase-plus-technical-specification.md?ask= ``` The question should be specific, self-contained, and written in natural language. 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.