Permanent Subscription PersistentSubscriptionNakEventAction

If a event from a permanent subscription could be handled I can send with the C# client a Fail back with the Action:

Retry

Stop

Skip

Park

Unknown

The first 3 Options are obvious. But what wil ldo bark ? The documentation says it is placed in a poison queue ? What will happen with this? And what does unknown do ?

Also is there a way to see this posion queue?

Many thanks in advance

Boas

unknown = let server decide what to do

park = write into the parked stream and continue later you can replay
parked messages.