OBS_VALUE: <ul><li><a href=http://www.admin.ch/opc/fr/classified-compilation/19940344/index.html target=_blank>Ordinance on aeronautic infrastructure(Ordonnance sur l'infrastructure aéronautique, RS 748.131.1,  23 November 1994, last updated on 1 January 2019, articles 29a. and 29b.)</a></li><li><a href=https://www.zurich-airport.com/business-and-partners/flight-operations/operating-licence#_ga=2.243003010.1849014382.1531821179-719965086.1531821179 target=_blank>Operation Regulation of Zurich Airport (Betriebsreglement)(Betriebsreglement für den Flughafen Zürich,  30 June 2011, last updated on 1 January 2016, article 15 and Annex 4 article 3)</a></li><li><a href=https://www.zurich-airport.com/business-and-partners/flight-operations/ground-handling target=_blank>Zurich Airport Website - Ground handling market at Zurich Airport Information</a></li></ul>