Alain:
In the Walker/Weinand book, German Clamshells, it says Reichsbahn Dienst.
In the Wheeler book, Seitengewehr, it says Reichsbahndirektion.
The Wheeler term makes a lot more sense than the use of the word Dienst, which I think means Service, used as in Honour of my Service.
Thank you for pointing this out.
Paul, do you have pictures?
John