Under a transitional arrangement following reunification, between 1989 and 1993 postal codes in the west were prefixed with 'W', e.g.: W-1000 30 (postal districts in western cities were separate from the postal code) and those in the east with 'O' (for Ost), e.g.: O-1xxx Berlin.
Dibawah perjanjian transisi setelah penyatuan, antara 1989 dan 1993 kodepos di bagian barat ditandai dengan 'W', contohnya W-1000 Berlin 30 (distrik pos di kota-kota barat dipisahkan dari kodepos) dan yang di timur dengan 'O' (untuk Ost), contohnya: O-1xxx Berlin.