Farrukh,
Apologies for the curve ball!
Here's the wikipedia reference:
and then I found open source implementations including this one:
Definately appealing that someone could use an XPDL designer tool to manage roles and actions in regrep...
XPDL is lightweight - its not intended to be a heavyweight BPMS - but it has the strong advantage of being easy for business functional staff to comprehend the diagrams and actions...
Ok - off to get a cup of tea so I can think better before I cause more disruption in the fabric of the universe!
Thanks, DW