Hi,HuiSheng
I think task variable only be accessed for the task who declare it ,while process variable can accessed fro all.For different task they may be have variables that have same variable name,but the value is different.Of course,I could do some extra work to achieve this,But ,It would be very conveniencent if task could declare it's own variables in jpdl.
I also think elements,such as task,state,should have an id attribute in jpdl def ,name attribute should only for human reading in jpdl photograph.