How are vehicles with a permissible total mass up to 2.8 t allowed to be parked here?

You answered correctly. This parking sign indicates that vehicles with a permissible total mass up to 2.8 tons are allowed to park with two wheels on the sidewalk, as shown in the images of the car and the caravan. Parking diagonally to the driving direction is not permitted unless specifically indicated by additional signs. This rule ensures safe and orderly parking without blocking the sidewalk or road. Always check for additional signs that might allow or prohibit different parking positions.