Several states have provision for treaty-related referendums (on international treaties). They are mandatory in some states in the case of accession to the European Union (Latvia) or, more generally, to a supranational community (Switzerland), international organisations in the case of a transfer of powers (Lithuania, Denmark, except when a decision is taken by a five-sixths majority of members of Parliament) or in the case of joining or leaving a community with other states (“the former Yugoslav Republic of Macedonia”) or of an association with other states (Croatia). It should be noted that the accession of Austria to the European Union was considered a total revision of the constitution and was consequently submitted to mandatory referendum. Switzerland also opts for a mandatory referendum in the case of joining collective security organisations.