When requested, IFM 5 should be used by an application to confirm the reception of an addressed binary message. An application should never acknowledge a binary broadcast message. If the interrogating application does not receive an IFM 5, when requested, then the application should assume that addressed AIS unit does not have an application attached to its Presentation Interface (PI). If there is any application at the AIS station, it should not respond if the “Acknowledge Required Flag” is set to 0.