For most visitors to East Berlin and the GDR, including persons who utilized the land transit routes (road and rail) between West Germany and West Berlin, their exposure to the  consisted of dealing with the members of the Pass and Control Units (, PKE) who processed travellers passing through the GDR's  (border crossing points).
Most people visiting East Berlin and the GDR, including those using land transportation links between West Germany and West Berlin, encountered the  through their interactions with the Pass and Control Unit personnel (PKE), who handled travelers at the GDR's border checkpoints.