LC 76 - What makes a msg WS-A?

Please could we discuss the following in the context of LC76?

When is an incoming message deemed to be a WS-Addressing message and 
therefore subject to the appropriate WS-Addressing validation?   Is it 
based on the presence of any WS-addressing Message Addressing Property? 
For example, does a message containing a reference parameter (but no other 
WS-Addressing information) need to result in a 
MessageAddressingHeaderRequired?    Or, for example, does the declaration 
of the wsa namespace rendor the message WS-Addressing?

Thanks
Katy