There is only one file type that uses the .XPDL extension:
Business process created for TIBCO iProcess or Business Studio business process management (BPM) software; contains code written in XPDL, the XML Process Definition Language; includes one or more processes that can be added to a iProcess or Business Studio business model.
The XPDL format was standardized by the Workflow Management Coalition, a global organization of individuals and groups engaged in managing business workflow. Therefore, XPDL files may be supported by other BPM applications besides iProcess and Business Studio.
Updated: June 12, 2011