> 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/resources/product-resources/end-of-life-product-documentation/os-detailed-path-network/os-detailed-path-network-technical-specification/code-lists/levelcodevalue.md).
# LevelCodeValue
The LevelCode value is used to indicate when a route is above or below normal ground level. The attribute is only applied where the level difference extends for distances greater than approximately 50m.
Routes that cross at different levels are not split at the intersection; those that are in tunnels or on bridges less than 50m long are given the default LevelCode attribute of Surface Level.
| Value | Description |
| -------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Surface Level | The route is at the same level as the surrounding terrain. This is the default value for RouteLink features. |
| Above Surface Level On Structure |
The RouteLink is supported or suspended above ground level on a manmade structure that extends for more than 50m.
For example, a road, track or path may be on a bridge, footbridge or viaduct.
|
| Below Surface Level Tunnel | The route passes through a specially built construction underneath the normal terrain surface primarily to avoid or reduce the effect of the terrain surface or to avoid an obstruction such as a river or mountain and extends for more than 50m. |
The LevelCode value is used to indicate when a route is above or below normal ground level. The attribute is only applied where the level difference extends for distances greater than approximately 50m.
Routes that cross at different levels are not split at the intersection; those that are in tunnels or on bridges less than 50m long are given the default LevelCode attribute of Surface Level.
**Above surface level on structure – example**
Example where a RouteLink is supported or suspended above ground level on a manmade structure.
**Below surface level tunnel – example**
This route passes through a specially built construction underneath the normal terrain surface.
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