I believe that Jan Still's note of 8/12/02 is correct. If S.D. is not for the town of Dusseldorf, then what was the Police unit marking for Dusseldorf ?. I have two unit marked SD's in my collection, 1921 dated S.D.VI.953, and 1915/1920 DATED S.D.I.275.R with the "R" crossed out. Just my 2 cents and 2 SD's worth.
|