as well as the territories annexed to Poland and the Soviet Union after World War II, which West Germany's government still claimed in that era until about 1970. When reunification came in 1990, the reserved codes (e.g. P for Potsdam) were indeed issued to East German districts in January 1991, often as originally planned and as they existed at that time. First changes Starting in the early 1970s, West German districts were extensively rearranged. In order to reduce their number and so simplify governance, different steps could be taken: city districts “swallowed” neighboring municipalities and thus grew. city districts lost their sovereignty and were integrated into the surrounding or neighbouring rural district. rural districts merged with one or several others, or were split up between neighbouring districts. single municipalities were moved between districts, as was deemed appropriate or practical. In each of these cases, the new districts had to be endowed with an area code. Again, various solutions were possible: the largest or most populous district bestowed its name and code upon the newly created unit. one former district gave its name and/or capital while another's area code was used for the new district. the new unit was given a new name yet continued to use an existing area code. the new unit was given a new name and created a new area code. In any case, the adamant rule was that one area code per district was valid and would be issued to any vehicle registered henceforth. Existing registrations would remain valid until the vehicle was removed from this district to be either relocated or permanently deregistered. Another rule, however, was abolished. Whereas rural districts had generally been named after their capital town, it was now possible to create new names, applying to geographical or historical features. As well it was possible to combine the names of the districts that had merged, either keeping one of their codes or creating a new one. Germany reunited When the GDR ceased to exist and Germany was reunited in its present size on 3 October 1990, new area codes were issued to the East German districts. In many cases they could be taken from the old lists that had been prepared before 1956: P stood for , EF for , SON for . Yet, a considerable number of codes was altered, either because a code which had been reserved for a district