# 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](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/type-annotations)
* [Tips](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/tips)
* [Compatibility](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/compatibility)
* [Standard Functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/standard-functions)
* [Maps and arrays Functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/maps-and-arrays-functions)
* Extension Functions
  * [Core functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/core-functions)
  * [Utility functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/utility-functions)
  * [Model functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/model-functions)
  * [Validation functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/validation-functions)
  * [Controls functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/controls-functions)
  * [XML functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/xml-functions)
  * [JSON functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/json-functions)
  * [HTTP functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/http-functions)
  * [Form Runner functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/form-runner-functions)
  * [Other functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/other-functions)
  * [Deprecated functions](https://doc.orbeon.com/~/revisions/-LF_uc1WMpa4Sd-n5tDb/xforms/xpath/extension-functions/deprecated-functions)