> 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/maps-and-imagery-portfolio/os-vectormap-local/os-vectormap-local-technical-specification/feature-types/railcline.md). # RailCLine Line representing the estimated centre line of a rail.
UML diagram of the RailCLine Feature Type, listing its six attributes. The feature type and its attributes are described in detail in the FeatureType RailCLine table.

UML diagram showing the RailCLine Feature Type in the GML supply

## RailCLine attributes ### polyline An ordered set of points forming a line feature. * **Type:** GM\_Curve * **Length:** N/A * **Multiplicity:** \[1] ### featureID A unique feature identification. IDs will be retained between iterations but will not be version controlled. * **Type:** CharacterString * **Length:** 38 * **Multiplicity:** \[1] ### featureCode A unique feature code to facilitate analysis and styling. * **Type:** [FeatureCodeValue](/os-downloads/products/maps-and-imagery-portfolio/os-vectormap-local/os-vectormap-local-technical-specification/feature-codes-and-descriptions.md) * **Length:** 5 * **Multiplicity:** \[1] ### featureDescription A description of the feature code. * **Type:** [FeatureDescriptionValue](/os-downloads/products/maps-and-imagery-portfolio/os-vectormap-local/os-vectormap-local-technical-specification/feature-codes-and-descriptions.md) * **Length:** 60 * **Multiplicity:** \[1] ### suppressed The suppressed value of the Road, used for cartographic styling. * **Type:** Boolean * **Length:** N/A * **Multiplicity:** \[1] ### inTunnel Determines whether the road alignment is in a tunnel and is used for cartographic styling. * **Type:** Boolean * **Length:** N/A * **Multiplicity:** \[1] --- # 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/maps-and-imagery-portfolio/os-vectormap-local/os-vectormap-local-technical-specification/feature-types/railcline.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.