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How does this program work as far as ensuring proper documentation of Schengen entries and exits for non-EU/EEA passport holders? In my experience, passport control agents often match up the entry and exit stamps (on the same passport page) to make sure I haven't overstayed in the Schengen zone. Let's say I enter the zone in Germany but then exit through France or Spain....how would the exit officer know I hadn't overstayed without a stamp in the passport?