Proportional representation allows companies to elect the majority of directors by proportional voting methods with periodic appointments. Companies may provide in their articles that not less than two-thirds of directors of a public company, or of a private company which is a subsidiary of a public company, shall be appointed according to the principle of proportional representation - by single transferable vote, cumulative voting, or other systems - with appointments made at regular multi year intervals and interim casual vacancies filled mutatis mutandis under the provisions applicable to casual vacancies.