You use the MQCreateTemporaryDestination function to create a temporary destination. You can use such a destination to implement a simple request/reply mechanism. When you pass the handle of a temporary destination to the MQSetMessageReplyTo function, the consumer of the message can use that handle as the destination to which it sends a reply.
Temporary destinations are explicitly created by client applications and are automatically deleted when the connection is closed. They are maintained (and named) by the broker only for the duration of the connection for which they are created. Temporary destinations are system-generated uniquely for their connection and only their own connection is allowed to create message consumers for them.