Returns the interchangeability warnings associated with the IVI session. It retrieves and clears the oldest instance in which the class driver recorded an interchangeability warning. Interchangeability warnings indicate that using your application with a different instrument might cause different behavior. You use this node to retrieve interchangeability warnings. The driver performs interchangeability checking when the IviDigitizer>>Inherent IVI Settings>>User Options>>Interchange Check property is set to TRUE. The node returns an empty string in the Interchange Warning parameter if no interchangeability warnings remain for the session. In general, the instrument driver generates interchangeability warnings when a property that affects the behavior of the instrument is in a state that you did not specify.