Soap Over Beep Question

Hi ALL!

I have a question regarding the SOAP Message Patterns.
In the section 4.1 under SOAP Message Patterns, the RFC 3288 says 
that in case of One-way Message exchange...

"....in which the client sends a "MSG" message containing 
an envelope, and the server immediately sends back a "NUL" 
message, before processing the contents of the envelope."

My question is: How does the server knows that the given MSG 
message containing the SOAP envelope is to be replied using 
the NUL message before processing the message? 

Since there is nothing in the syntax of SOAP Over Beep messages
which suggests how the message is to be replied with (i.e. if
this is a one way, 2 way or multi answer response)..the server 
will only know about the type of message pattern being used only 
from processing the SOAP message. 

Please enlighten me on this. I may be completely missing something.

Thanks,
Rohit Karlupia