International organizations — Status — International Air Transport Association (“IATA”) — Whether a “public international organization” — Non-governmental and quasi-governmental organizations — IATA-Switzerland Headquarters Agreement, 1976 — Agreements concerning fiscal exemption for “public international organizations” — Requirement of approval by cantonal authorities — Immunity — Organization and its officials — Fiscal immunity

States — Federal States and confederations — Agreement between federal government and international organization providing for immunity from cantonal taxes — Requirement of cantonal approval — Whether provision for referendum required

Treaties — Conclusion and operation — Constitutional limitations — Requirement of approval by cantonal authorities — The law of Switzerland