Whenever planned or already held World Expositions are in the news, the “category” of the exposition is mentioned. I’ve looked up the Website of the International Exhibitions Bureau that’s organizing the events, and they mention a “general classification” with tow categories called “Registered Exhibitions” and “Recognised Exhibitions”. In their list of past exhibitions, however, the terms “Specialized Exhibition” and “Universal Exhibition” come up, with some others (like “General Exhibition Category I”, Montreal 1967). What’s the logic in this classification scheme, what are the criteria relevant for declaring an exhibition Category II instead of I?
Besides, is there a regularity in the intervals in which World Expositions are held? The list suggests it’s irregular, but maybe there’s method in this apparent madness.
And one last question: What’s the usual term for those events in English-speaking countries? Exhib- or expos-ition?