What is the third number in subscription of Topic in Service Bus Explorer

Question

I am using Azure Service Bus Explorer, What is the third number of Subscription in Service Bus Explorer, For Example, topicname - Subscriptions - SubscriptinName(12,13,0), the first one(12) is the number of the messages the second number(13) is the number of the messages in dead letter queue, what is the third number 0?

Answer 1

Looks like the answer is here.

It looks like it displays the TransferDeadLetterMessageCount.