Bf 109F-2 w.nr.8240 "white 0" => explanations ???

Hello,
One of my future projects is a Bf 109F-2 (w.nr.8240 "white 0") flown by Karl-Heinz Weber in 7./JG51 during Summer 1942.
This aircraft was previously flown by Walter Oesau at the beginning of Operation Barbarossa as Gruppenkommandeur III./JG3 (double chevron marking).
I would like to know if this code "0" was often used in fighter units and the reasons... I know it was sometimes used in ground-attack units...
TIA
Stéph

Hello,
I found others aircrafts (FW 190A) of 7./JG51 with markings "white 0" in the book "Die Jagdfliegerverbände der Deutschen Luftwaffe 1934-1945, teil 12/II". It seems it was common in this unit. But no explanation.