The airline contractors' additional "security" screening/document check. They ask "questions" of passengers when say flying DL from AMS to the US. The kind of people who try to get US citizens to provide non-existent, illegal Danish ID to fly on planes from AMS to the US only because the roundtrip US-bound ticket for the US citizens starts and ends in Denmark.

This Q&A checking/paperwork can be done near the airline check-in counters on the open/public landside of the airport, or it can be done at a real gate or pseudo-gate area airside when flying US carriers to the US from AMS.