Postal codes in Austria were introduced in 1966 and consist of four digits.
The first indicates the state:
The second number indicates the regional area in the state, the third number is for the routing allocation, following railways and post car routes and the fourth number indicates the post office. Every post office has its own number. There are some exceptions to this rule: In Vienna, the second and third numbers show the district, so 1120 would be the twelfth district. Also, some cities close to the German border in Vorarlberg have Austrian and German postcodes.
There are also some special post codes: the airport has its own post code (1300), the UN (1400) and some big companies also have their own post code, for example the ORF, the Austrian National Broadcasting Service (1136). These special post codes are not listed in the public phonebook, though there is a book which contains them and can be bought at an Austrian post office.