Do you sometimes wonder what the letters above the Rollei name mean?
All of these letters have to do with German Patents and Trademarks.

DBP is: Deutsches Bundes Patent.

DRP is: Deutsches Reichs Patent.

DBGM is: Deutsches Bundes Gebrauchs Musterschutz
a Trademark.

DRGM is: Deutsches Reichs Gebrauchs Musterschutz
a Trademark.

I do not speak or understand German, but I think you get the general meaning.  They simply mean that patents have been obtained for the camera. And the others are Rollei Trademarks.

Hope this helps!