Well, its matter of writing. KG 355 yelded plenty responses whilst '
Giggling', then one can find info on III Gruppen *
third Gruppen.
I think "
flugaustrag" can indeed be training flight as date is between 'events' when Germany added terretories to its
Fatherland, and rest is code for the individual aircraft.
Type be Heinkel He 111 *Arabic, not Roman figures, and code 55+
O37 = 55 the fifth Bomber Geschwader (or Gruppen, or assigned unit to that Luftkreis) in
Luftkreis 5, the individual letter
O *
Otto of seventh
Staffeln in third
Gruppe *they having Gruppe first, then Staffeln.
This later became KG 53, then getting codeA1 and summer 1939 is the time when this was done althoug I do not have exact date for KG 53, as it was not a Ju 88 unit. (55+
O37
then theoretically becoming A1+
OR )
Explained below.
http://www.luftarchiv.de/
select
Luftfahrtindustrie
and
Anhang I