Late reply, I know, but Wikipedia explains all the different plates and their purposes quite nicely:

http://en.wikipedia.org/wiki/German_car_number_plates

__________________
1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)