I've seen this before but had never spent much time thinking about......Till Now!!
First, it's a nice image. I'd like to have a look at a higher res version but still this is not bad.
I bet the after market "deck and coping kit" snapped right onto the existing threaded panel post.
Or what ever they are called. Where the fokker nuts go. Lol
The cross doesn't match any production machines that I can see. That is with one exception.
The DVL Dr.I 528 can be seen sporting the same style cross on the fuselage. (circa mid 1930's)
I dont think they are related however. The crosses appear to have been made by simply drawing a
straight edge to opposite corners. Quick and easy, perhaps, if a stencil is not available.
Also, while earlier Fokker's can be seen with varying cross types....none I have seen, are like this one.
An anomaly for sure
The caption from Lloyd's site seems to match other information on 423. Other than the Jasta Schule
part. Not sure where that comes into the story.
I think that the photo was taken at the Fokker factory field. Maybe it was being tested by/at Bauaufsicht 13.
Perhaps it is the test pilot Weidner in the photo??
The crosses themselves were probably so as not to be shot at by friendlies on the ground.
Note the lack of crosses on the top wing. They would not have sent out a plane to an operational post
without them. Hence my thought that this is taken at Fokker.
Who knows. Cool photo still