Yes. But it's not used in the U.S. & Canada. In the U.S. and Canada the standard letter size is 8.5" wide by 11" long which is equivalent to 216mm by 279 mm. The so-called international standard is called "A4" and measures 210 mm by 297 mm. (That's not a typo -- U.S. is 279, A4 is 297.) There is a logic to the size chosen for the international standard: If you divide the length of the longer side by the length of the shorter side, you get 1.4142. This is the RATIO of the long side to the short side and equals the square root of 2. If you put two sheets of A4 paper side by side so their edges touch, and if you consider them as one large sheet of paper -- you can divide the length of the newly-formed long side by the new short side, and you will get the same ratio -- the square root of 2. This is useful when you are copying pages and need to reduce or enlarge the image -- like wanting to reduce 2 pages to fit on one page. The resulting reduced image will exactly fit the paper it's copied onto. The margins will stay the same. I'm sure there are other "good reasons," too. == The practical and aesthetic advantages of the "square root of 2" aspect ratio for paper sizes were probably first noted by the physics professor Georg Christoph Lichtenberg (University of Göttingen, Germany, 1742-1799) in a letter that he wrote 1786-10-25 to Johann Beckmann. The...paper format...[came to some countries in the following years]: Belgium (1924), Netherlands (1925), Norway (1926), Switzerland (1929), Sweden (1930), Soviet Union (1934), Hungary (1938), Italy (1939), Uruguay (1942), Argentina and Brazil (1943), Spain (1947), Austria (1948), Romania (1949), Japan (1951), Denmark and Czechoslovakia (1953), Israel and Portugal (1954), Yugoslavia (1956), India and Poland (1957), United Kingdom (1959), Venezuela (1962), New Zealand (1963), Iceland (1964), Mexico (1965), South Africa (1966), France/Peru/Turkey (1967), Chile (1968), Greece/Simbabwe/Singapur (1970), Bangladesh (1972), Thailand and Barbados (1973), Australia and Ecuador (1974), Columbia and Kuwait (1975). [The paper size is part of a complete system of paper sizes for various uses, called the "DIN paper format." This] format system finally became both an international standard (ISO 216) as well as the official United Nations document format in 1975 and it is today used in almost all countries on this planet. In 1977, a large German car manufacturer performed a study of the paper formats found in their incoming mail and concluded that out of 148 examined countries, 88 already used the A series formats then. [Source: Helbig/Hennig 1988] ---http://www.cl.cam.ac.uk/~mgk25/iso-paper.html For a long discussion of religious/numerological reasons for choosing the A4 paper size -- including eventually relating "ISO216" to the number "666" -- please see: http://homepage.virgin.net/vernon.jenkins/PS.htm