> 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 %}


---

# 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:

```
GET https://docs.os.uk/os-downloads/products/water-portfolio/os-open-rivers/os-open-rivers-technical-specification/esri-shapefile-overview.md?ask=<question>
```

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.