about the onMessage method of MDB

Hi I have a theoretical question about this method, I post it because I fear not having understood well the logic behind it.
Application exception are defined as exceptions which the client is expected to handle.
Any Exception can be made an application exception by annotating it with @ApplicationException.
A Message Driven Bean can throw only unchecked exceptions from its onMessage method so if I annotate my RuntimeException with @ApplicationException I can do it.
But a MDB does not have a client invoking it so does it make sense to have this possibility?

Please refer the below,

Chapter 5 - Message Driven Bean Component Contract
5.4 - Protocol Between a Message-Driven Bean Instance and its Container
5.4.18 - Dealing with Exceptions

The below URL is where you can download the EJB3.1 specs from.
EJB Specs

Hope it helps.

Regards,
Anirudh.