How does WMQ exchange DLQ information between remote and local queue managers?

When the local queue manager receives an AMQ error message in it:

09/13/12 08:00:19 - Process (3017.20) User program (mqm) (amqrmppa_nd) AMQ9544: messages are not placed on the destination queue.

Explanation: During processing of the TO_QM_QD2T1_C1 channel, one or more messages cannot be placed in the destination queue and attempts to queue them with a dead letter. The queue location is 2, where 1 is the local dead letter queue, and 2 is the remote dead letter queue.

... What is the mechanism by which MQ exchanges such information? Is there a built-in tool in the program’s API channel itself or information exchange in the form of discrete messages placed on SYSTEM.CLUSTER.COMMAND.QUEUE(in the case of a cluster)? Given that this can happen in a situation where a remote queue is defined, only with simple pairs of sender / receiver channels and without the corresponding COMMAND QUEUE, I could assume that this would be processed through the channel communication processes ... just interesting ...