Q-/D-mode classification for incoming GIST Data messages

Greetings,

Regarding the new GIST ID-16, how can I differentiate Q-mode and D- 
mode Data messages in a middlebox, when the GIST Data message is sent  
with S=1 in GCH?

 From what I understand, now that RAO has been removed from Path- 
Coupled and Loose-End Q-mode, the only way to identify an incoming  
GIST packet as Q-mode message, is to compare the IP and MRI addresses,  
when S=0 in GCH. (This is presuming that the message is sent to the  
well-known UDP port, the node contains the signaling application and  
the payload has the magic number before GIST data).

One simple solution that comes into mind, would be to add a "Q"-flag  
to GIST Common Header, that would be set whenever the message is a Q- 
mode message.

BR, Nuutti