More codes may be defined in future versions of the software.
Some MQSeries-related errors will not (i.e. cannot) result in a negative action notification. For example, if one does not define a reply queue, there is no way to send this information back. This is also the case if the WindowsEnabler PC is unable to open the reply queue, or to put messages on it. If this happens, the request message will be moved to the dead-letter queue (provided there is one), so that an operator can inspect which request went wrong. In addition, the WindowsEnabler/MQSeries PC will log the error.