# AddressBase Fundamentals The following AddressBase Fundamentals pages provide an overview of the 'family' of AddressBase products. They cover key elements of design for AddressBase products, including data formats, classification scheme, product supply, coordinate reference systems, currency, precision, and data sources, amongst other topics. * [Release notes](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/release-notes.md) * [AddressBase product family](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/addressbase-product-family.md) * [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-fundamentals/currency-completeness-and-precision.md) * [Product supply](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/product-supply.md) * [Code lists and enumerations](/os-downloads/products/addresses-and-names-portfolio/addressbase-fundamentals/code-lists-and-enumerations.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) These pages should be used in conjunction with the detailed technical specifications for each product (which can be found under the top-level product page for each individual product from the left-hand-side menu). --- # Agent Instructions: 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-fundamentals.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.