XML-Based Process Definition Language. The Workflow Management Collation (WfMC) created this standard language to describe how workflow tools can communicate information about business processes with each other over the Internet.

XPDL is an XML dialect for process descriptions and was adopted by the Workflow Management Coalition. Using this scheme processes can be defined in XML and exchanged between workflow management systems of different producers who support this standard. http://www.wfmc.org

The XML Process Definition Language (XPDL) is a format standardized by the Workflow Management Coalition to interchange Business Process definitions between different workflow products like modeling tools and workflow engines. XPDL defines a XML schema for specifying the declarative part of workflow.