Shimamura-san's modification of Marty's words (edited version): When messageOrderSemantics is set to Guaranteed , the Receiving MSH shall preserve in persistent storage all required SOAP Header information, including SequenceNumber, needed to keep the Message Order semantics of the last message in the conversation sent in order to the application until either a subsequent in-order message arrives or until the conversation ends (no matter how long the conversation exists). The Receiving MSH shall preserve in persistent storage the ConversationId of an in-progress conversation until that conversation ends (no matter how long the conversation exists). Does this meet everyone's requirements? I think we will get some flack since this guarantees slow accumulation of old ConversationIds in persistent Storage. In the second paragraph, do we need to say Conversations with messageOrderSemantics set to Guaranteed ? Do we need messageOrderSemantics? If MessageOrder is present, why would messageOrderSemantics ever be NotGuaranteed ? The problem is MessageOrder tied to ConversationId. MessageOrder is a very time limited situation while ConversationId can be unlimited -- not a good match. Regards, David.