The Operational Status Mode (with Code 00) has field "Reserved for Receiving ATC Services" (bit 29 within ME). Though it is marked reserved, it seems to be in use.
At least, ED129B uses that field as "Receiving ATC Services", no mention of anything being reserved.
This is applicable to Surface and Airborne messages.
The Operational Status Mode (with Code 00) has field "Reserved for Receiving ATC Services" (bit 29 within ME). Though it is marked reserved, it seems to be in use.
At least, ED129B uses that field as "Receiving ATC Services", no mention of anything being reserved.
This is applicable to Surface and Airborne messages.