Due to the regulations of the Bureau International des Expositions (International Exhibitions Bureau), which is responsible for negotiating and deciding all matters relating to universal exhibitions, an entity must be a formal member state of the organization to participate in a World Expo and to set up a "national pavilion" at the expo.
由於負責協調、審議歷屆世博會的「國際展覽局」規定，必須是該組織的正式「會員國」才有資格參與世博，並在展覽期間籌設「國家館」。