Optional read-only. The PROPID_Q_INSTANCE property identifies a specific public queue.
The PROPID_Q_INSTANCE property identifies the created public queue (it is not an instance of an open queue). This property is set by MSMQ when the application calls MQCreateQueue. An MQ_ERROR_PROPERTY_NOTALLOWED error is returned if any attempt is made to set this property.
PROPID_Q_INSTANCE only applies to public queues. An MQ_INFORMATION_PROPERTY_IGNORED error is returned if an attempt is made to get this property for a private queue.
To find the identifier of a public queue, pass PROPID_Q_INSTANCE to MQGetQueueProperties or MQLocateBegin (when starting a query) and examine its returned value.
MQCreateQueue, MQGetQueueProperties, MQLocateBegin