> 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/addressbase-technical-specification.md). # AddressBase Technical Specification AddressBase provides an address product containing both residential and commercial addresses where a Local Authority address has been matched to a Royal Mail PAF address. This allows users to link additional information about a property to a single address. The product also provides enhancements to the Royal Mail PAF data by assigning an X and Y coordinate on British National Grid and an ETRS89 projection, as well as a primary level classification, and a representative point code describing the positional quality. This technical specification includes the following sections: * [Data formats](/os-downloads/products/addresses-and-names-portfolio/addressbase/addressbase-technical-specification/data-formats.md) * [Supply and update](/os-downloads/products/addresses-and-names-portfolio/addressbase/addressbase-technical-specification/supply-and-update.md) * [AddressBase Premium structure](/os-downloads/products/addresses-and-names-portfolio/addressbase-premium/addressbase-premium-technical-specification/addressbase-premium-structure.md) * [Feature types](/os-downloads/products/addresses-and-names-portfolio/addressbase/addressbase-technical-specification/feature-types.md) * [Code list and enumerations](/os-downloads/products/addresses-and-names-portfolio/addressbase/addressbase-technical-specification/code-list-and-enumerations.md) * [CSV to GML mapping](/os-downloads/products/addresses-and-names-portfolio/addressbase/addressbase-technical-specification/csv-to-gml-mapping.md) * [Example records](/os-downloads/products/addresses-and-names-portfolio/addressbase/addressbase-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, and the optional `goal` query parameter: ``` GET https://docs.os.uk/os-downloads/products/addresses-and-names-portfolio/addressbase/addressbase-technical-specification.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. 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.