# OS OpenMap – Local Technical Specification OS OpenMap – Local (OML) is the most detailed ‘street level’ open mapping product available and is designed to provide contextual mapping for your applications or web pages. It offers customers and OS Partners a clear contextual view of the world, whilst also enabling the undertaking of analytical activities. OS OML data is available as either pre-styled static images (raster) or interactive vectorised features in a selection of pre-defined or customisable styles. The vectorised format of the product consists of multiple layers of feature information which can be individually interrogated, displayed and styled to suit your needs. [Stylesheets](https://github.com/OrdnanceSurvey/OS-OpenMap-Local-stylesheets) are available for this product in GitHub. The rasterised layers provide pre-defined static contextual mapping that is designed to allow customers to overlay their own data clearly. More information on styling can be found in the [Getting Started Guide](https://docs.os.uk/os-downloads/products/maps-and-imagery-portfolio/os-openmap-local/os-openmap-local-getting-started-guide). OS OML contains functional sites, greenspace, important buildings and Department for Transport (DfT) numbers in order to facilitate alignment with other OS products. When using OS OML for contextualised mapping, the nominal viewing scale is 1:10 000, with a recommended viewing scale range of 1:3 000 to 1:20 000. ## Index The OS OML technical specification is broken down into the following topics: * [Data structure](https://docs.os.uk/os-downloads/products/maps-and-imagery-portfolio/os-openmap-local/os-openmap-local-technical-specification/data-structure) * [Feature types](https://docs.os.uk/os-downloads/products/maps-and-imagery-portfolio/os-openmap-local/os-openmap-local-technical-specification/feature-types) * [Code lists](https://docs.os.uk/os-downloads/products/addresses-and-names-portfolio/os-open-names/os-open-names-technical-specification/code-lists) --- # 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/maps-and-imagery-portfolio/os-openmap-local/os-openmap-local-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.