No, Arvola is right. We decided a message could be delivered from the MSH to the Application AFTER TTL. TTL is the time it must be delivered to the To Party MSH. If this is not true, then the receiver could just hold any message he didn't like until after TTL and then discard, regardless of any Acknowledgments. The sending of an Acknowledgment constitutes a commitment by the MSH to deliver to the Application (what the Application does is undefined). Regards, David.