The return codes from synchronous functions indicate whether the function completed successfully. MIBConnect and MIBDisconnect are synchronous functions.

The return codes from asynchronous functions indicate only whether CMIP services received the request or response. All API functions, except MIBConnect and MIBDisconnect, are asynchronous functions.

All of the API functions that return an invoke identifier are asynchronous functions. The invoke identifier can be used to correlate the response to the original request. A return code of zero from the API function indicates that the request was successfully sent to CMIP services. The confirmation from the target of the request serves as the acknowledgement.

On confirmed requests, the object sending the request receives a MIB.ServiceError message or a CMIP message (ROIVapdu, RORSapdu, or ROERapdu). On unconfirmed requests, the object sending the request receives a MIB.ServiceAccept message or a MIB.ServiceError message.

Because responses are never confirmed, the object sending the response receives a MIB.ServiceAccept message or a MIB.ServiceError message.