Postal district numbers for the addressing and sorting of mail were used in the suburban area of Melbourne, Victoria, Australia from February 1928 until their 1967 replacement by the Australia-wide postcodes. They were based on the London codes with a letter (or letters) denoting the direction from the main city post office and a number appended to, generally, correlate with the relative distance. An earlier system from around 1923 with twelve districts or 54 which had failed due to neglect was replaced.