Hi Paul
Yes, rather funny isn't it, with ca 1200 built of everything!
I admit I don't have Griehl's Airdoc book. Guess I am still waiting for a 'bigger' book about the Do 17, something like the Classic publications.
What I find strange is that they should redignate two prototypes as L-1 and L-2 respectively. These two designations are production designations, so perhaps they simply were notched up as that just in case any production would follow?
Anyway thanks for letting me know the designation really existed.
Cheers
Stig