a stamp activates or acknowledges the continuing leave conferred in the passport bearer's entry clearance. Under the Schengen system, a foreign passport is stamped with a date stamp which does not indicate any duration of stay. This means that the person is deemed to have permission to remain either for three months or for the period shown on his visa if specified otherwise. Member states of the European Union are not permitted to place a stamp in the passport of a person who is not subject to immigration control. Stamping is prohibited because it is an imposition of a control to which the person is not subject. Passport stamps may occasionally take the form of sticker stamps, such as entry stamps from Japan. Depending on nationality, a visitor may not receive a stamp at all (unless specifically requested), such as an EU or EFTA citizen travelling to an EU or EFTA country, Albania, or North Macedonia. Most countries issue exit stamps in addition to entry stamps. A few countries issue only entry stamps, including Canada, El Salvador, Ireland, Mexico, New Zealand, Singapore, United Kingdom and the America. Australia, Hong Kong, Israel, Macau and South Korea do not stamp passports upon entry nor exit. These countries or regions issue landing slips instead, with the exception of Australia who do not issue any form of physical evidence of entry. Visas may also take the form of passport stamps. Immigration authorities usually have different styles of stamps for entries and exits, to make it easier to identify the movements of people. Ink colour might be used to designate mode of transportation (air, land or sea), such as in Hong Kong prior to 1997; while border styles did the same thing in Macau. Other variations include changing the size of the stamp to indicate length of stay, as in Singapore. In many cases passengers on cruise ships do not receive passport stamps because the entire vessel has been cleared into port. It is often possible to get a souvenir stamp, although this requires finding the immigration office by the dock. In many cases officials are used to such requests and will cooperate. Also, as noted below, some of the smallest European countries will give a stamp on request, either at their border or tourist office charging, at most, a nominal fee. Exit controls Whilst most countries implement border controls both at entry and exit,