From
http://www.airportcity-frankfurt.com...0.controls.htm
Passport/ID check:
For many destinations within the European Union, the "Schengen Treaty"
has eliminated this check. These include: Austria, Belgium, Denmark, Finland,
France, Germany, Greece, Iceland, Italy, Luxemburg, the Netherlands, Norway,
Portugal, Spain and Sweden. When you are traveling to countries not covered by
this treaty, your ID (if you are a citizen of an EU country) or passport will be checked.