World Expos (formally known as International Registered Exhibitions) encompass universal themes that affect the full gamut of human experience, and international and corporate participants are required to adhere to the theme in their representations. Registered expositions are held every 5 years because they are more expensive as they require total design of pavilion buildings from the ground up. As a result, nations compete for the most outstanding or memorable structure—for example Japan, France, Morocco, and Spain at Expo '92. Registered Expositions include Brussels Expo '58, Montreal Expo 67, Vancouver Expo 86, Osaka Expo '70, and Seville Expo '92. Sometimes prefabricated structures are used to minimize costs for developing countries, or for countries from a geographical block to share space (i.e. Plaza of the Americas at Seville '92).