I don't know if this is a problem or not. TimeToLive is a time, not an interval, and should probably be set to current time plus 1/2 RetryInterval (half of the round trip from sender to receiver back to sender). Won't this have to be recalculated each retry? Won't this invalidate the signature? Maybe I'm getting the correct value of TimeToLive wrong? What in the world should this be? Maybe this is more along the lines of This PO is valid for 30 days so this value should be set to current time plus 30 days? In any case, we probably need to clarify the spec. Regards, David Fischer Drummond Group.