cipher or three-letter-initalism

I used to pride myself on being able to recognize a good deal of the county-coded car licensing-system of Germany.
I got pretty good at telling who was a long way from home and it was an engrossing meals to learn about different communities when a unfamiliar plate passed by, but I think now I am falling behind. As of mid-July, however, the competent authorities of Frankonia and other localities have released, re-introduced the naming convention of 1973 when smaller jurisdictions were annexed into their surrounding counties. The decision has proved wildly popular as a chance for expression, personalization and local patriotism and slowly the new license plates are appearing on the road. As the trend is sure to take on, it's chaos, I think, and I have a lot more to learn. H told me that the new, nostalgic abbreviations often were used in the classifieds for properties and he never knew what MET or KÖN or GEO meant.