> For the complete documentation index, see [llms.txt](https://doc.orbeon.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.orbeon.com/xforms/xpath.md).

# XPath

Orbeon Forms uses [XPath 2.0](https://www.w3.org/TR/xpath20/) as expression language.

This page and sub-pages describe XPath usage and the Orbeon Forms XPath function library. The documentation is split into:

* [Type annotations](/xforms/xpath/type-annotations.md)
* [Tips](/xforms/xpath/tips.md)
* [Compatibility](/xforms/xpath/compatibility.md)
* [Standard Functions](/xforms/xpath/standard-functions.md)
* [Maps and arrays Functions](/xforms/xpath/maps-arrays.md)
* Extension Functions
  * [Core functions](/xforms/xpath/extension-functions/extension-core.md)
  * [Utility functions](/xforms/xpath/extension-functions/extension-util.md)
  * [Model functions](/xforms/xpath/extension-functions/extension-model.md)
  * [Controls functions](/xforms/xpath/extension-functions/extension-controls.md)
  * [XML functions](/xforms/xpath/extension-functions/extension-xml.md)
  * [JSON functions](/xforms/xpath/extension-functions/extension-json.md)
  * [HTTP functions](/xforms/xpath/extension-functions/extension-http.md)
  * [Form Runner functions](/xforms/xpath/extension-functions/extension-form-runner.md)
  * [Other functions](/xforms/xpath/extension-functions/extension-other.md)
  * [Deprecated functions](/xforms/xpath/extension-functions/deprecated-functions.md)