Countries usually have different styles of stamps for entries and exits,to make it easier to identify the movements of people.The shape of the stamp and the colour of the ink may also provide information about movements (whether departure or arrival). In Hong Kong,prior to and immediately after the 1997 transfer of sovereignty,entry and exit stamps were identical at all ports of entry,but colours differed. Airport stamps used black ink,land stamps used red ink, and sea stamps used purple ink. In Macau,under Portuguese adminstration,the same colour of ink was used for all stamps,but the stamps had slightly different borders to indicate entry/exit by air,land,or sea.