Orbeon Forms uses XPath 2.0 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
Tips
Compatibility
Standard Functions
Maps and arrays Functions
Extension Functions
Core functions
Utility functions
Model functions
Validation functions
Controls functions
XML functions
JSON functions
HTTP functions
Form Runner functions
Other functions
Deprecated functions