you can see that at 17th. page there is a schema of workflow states.in there there is an arrow between dormant and halted which is named restart.but when i tried to restart a halted workflow with restart() metod of workflow, it gives an error like "the workflow is not running".but i f i try to resume the halted WF goes to state running.as a result , in that schema the restart arrow does not run it is false i think.if i am not wrong, this conference gived by EMC.may be you want to correct this "error".
Best regards.