Good evening Char and Nick !
indeed a nice example in German military bureaucracy termination for your collections
.
On my opinion, A.d.D. means "Auf dem Dienstweg", which can be translated as "through the official channels", here to the
Air Fleet Command Reich ,
while those statistical units as Quartermaster General, Wehrmachtsauskunftsstelle e.g. received the information directly, not on the longer way through the official channels.
Best wishes !
Horst Weber