I wonder what is the shortest adress that works in Germany. Central Mannheim has streets (or rather squares) which are identified by a combination of a single l

I wonder what is the shortest adress that works in Germany. Central Mannheim has streets (or rather squares) which are identified by a combination of a single letter and a single digit. This is then followed by the number of the house. But sometimes a building occupies a whole square. So for example E5 68159 Mannheim is the address of the city hall. One should get away with using the number plate abbriviation "MA" for "Mannheim". So something like H5 68159 MA should work too. And since the zip code identifies the city H5 68159 might work as well. And perhaps even H5 MA or simply H5 if you post the letter in Mannheim itself. Another possibility for short addresses is that some companies or agencies in Germany have their own postal code. So just writing their five-digit-code on the envelope should suffice.