Hallo again Dénes
I assume you know about this page?
http://www.freeweb.hu/horac/talalat.php?GTA=t97
A also believe you are in a better position to ask those responsible if they have anything further. I have had a bit of a struggle to translate what they say into Swedish....
I am not sure there was any specific logic behind the application of the Dienstnummer in Austria. Mind you I have not studied them to see if there is, so there may well be you know.
Just like in Hungary these Dienstnummer were initially covered up by civil registrations, just like the LüH numbers in Hungary. Nothing strange in that since all nations forbidden to have an airforce in 1919 did the same thing.
Cheers
Stig