郵政式拼音以威妥瑪拼音爲根據，不過採用一些已經普及化嘅地名拼法。此外，一些地方使用當地方言或古音來拼寫其地名。
The postal pinyin is based on the Weituma pinyin, but it uses some of the place names that have become popular. In addition, some places use local dialects or archaic sounds to spell their place names.