All visitors must hold tickets and documents for return or onward travel. Visitors should also have at least US$30 per day to fund their visit, unless a Danish citizen meets them at the airport and officially vouches for them. Denmark is a signatory to the Schengen agreement, which also includes the following countries: Austria, Belgium, Finland, France, Germany, Greece, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain and Sweden. All these countries issue a standard Schengen visa that, in principal, allows the holder to travel freely within the borders of all.