Trieste Airport carries the IATA code TRS — the three letters printed on boarding passes and baggage tags — and the ICAO code LIPQ, used in flight plans and by air traffic control. It serves Ronchi dei Legionari/Trieste, Italy.
IATA codes are assigned by the International Air Transport Association for passenger-facing use; the four-letter ICAO code encodes region and country and belongs to the operational side of aviation.