Unknown base marking of 3.7cm German shell case

[37bis]

Hello everyone,
I would like to identify this unusual horizontal (and not circular) base marking on a German 37x94r shell case.
And why “Leichte” (= light) ?
Thanks.
hanks

 

[Gspragge]

I've never come across this before, one can guess at reduced charge ?

 

[Hoeksel]

I would expect Leichte to reflect on 1) light case (weigh and compare with other cases from the period) or 2) for lighter gun. Either way it looks experimental and it is the first time I see this head stamp.