Alternatively, the stamps activate and/or acknowledge the continuing leave conferred by the individual's entry clearance. Other authorities, such as those in Schengen member states, simply stamp a passport with a date stamp that does not indicate any duration and this stamp is taken to mean either that the person is deemed to have permission to remain for 90 days within a 180-day period or an alternative period as shown on their visa, whichever is shorter.
In some cases, stamps are activated or validated by the individual's entry clearance. In contrast, authorities in Schengen member states simply stamp a passport with a date without specifying a duration, and this stamp implies that the person has permission to stay for 90 days within a 180-day period or an alternative period shown on their visa, whichever is shorter.