Paper size a number of different sizes were defined for large sheets of paper, and paper sizes were defined by the sheet name and the number of times it had been folded. Thus a full sheet of "royal" paper was 25 × 20 inches, and "royal octavo" was this size folded three times, so as to make eight sheets, and was thus 10 × inches. Imperial sizes were used in the United Kingdom and its territories. These sizes are no longer commonly used since the UK switched to ISO sizes. Many of these sizes were only used for making books (see bookbinding),
Letter sheet Special stationery on thin sheets of paper, called "Air Letter Cards" were available in Iraq as early as 1933. The sheets were folded to the size of the blue border, and gummed flaps were used to seal the sheet. Douglas Gumbley, director of Posts to the Iraq Government in the 1930s, realised there was a need for a lightweight form for use in the developing air services in, and through, the Middle East because regular overland mail was charged by weight and varied in size and seemed likely to be too expensive for airmail service. He personally copyrighted the product