In 1933 the regional system was changed to a two letter - three number format. Front plates were rectangle, rear plates were square shaped. In the 1940s, in and shortly after the years of the World War II the format was temporarily changed to one letter - four number. From 1948 the previous two letter - three number format returned. In the years of the harsh communism there were only a few private cars, most of the vehicles were owned by the state, there was no need of expanding the number of characters.