> For the complete documentation index, see [llms.txt](https://docs.os.uk/osngd/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/osngd/code-lists/code-lists-overview/gaugevalue.md). # gaugevalue The distance between the inside faces of the individual rails.

Label	Definition
Broad	A set of metal tracks that are greater than 1 435mm apart.
Monorail	A single rail serving as a track for a wheeled vehicle.
Narrow	A set of metal tracks that are closer together than 1 435mm.
Standard	A set of metal tracks that are 1 435mm apart.

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