> 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-fundamentals/street-names-and-numbering.md). # Street names and numbering A critical step in the creation of an address is undertaken within each Local Authority by the dedicated Street Name and Numbering (SNN) custodian and the Scottish Local Street Gazetteer (LSG) custodians, who allocates the official street name and building information. The SNN/LSG custodian has a statutory obligation to provide SNN/LSG information for all addresses within their administrative area. Once the SNN/LSG custodian has fulfilled their statutory obligation for initial capture, the LLPG/OSG custodian will maintain the address for the life of the address record. The official street name and building information for new properties captured by the SNN/LSG custodians is provided to Royal Mail who then allocate a postcode to the address. --- # 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-fundamentals/street-names-and-numbering.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.