> 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/water-portfolio/os-open-rivers/os-open-rivers-technical-specification/esri-shapefile-overview.md).

# Esri shapefile overview

OS Open Rivers is supplied as an Esri shapefile. Shapefile is an open file format to store geometry and attribute information about spatial features.

### Attribute mapping <a href="#id-4.1-attribute-mapping" id="id-4.1-attribute-mapping"></a>

The naming of attributes between GML and Esri shapefile is different; shapefiles limit attribute names to 11 characters, whereas GML has no limit. The tables in the following pages map the GML attribute name to its Esri shapefile equivalent for the WatercourseLink and HydroNode features:

* [WatercourseLink](/os-downloads/products/water-portfolio/os-open-rivers/os-open-rivers-technical-specification/esri-shapefile-overview/watercourselink.md)
* [HydroNode](/os-downloads/products/water-portfolio/os-open-rivers/os-open-rivers-technical-specification/esri-shapefile-overview/hydronode.md)

{% hint style="info" %}
GML includes attributes which describe the geometry of the features; this is not applicable to shapefile as they are separated by their geometry.

The use of an asterisk symbol (\*) in the tables indicates that a particular attribute is not mapped in that format, for example, the centrelineGeometry attribute has no shapefile equivalent.
{% endhint %}


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