Although single-sided printing wastes paper, it is more suitable for non-professional typesetters (such as students and office clerks) to use non-professional typesetting software to discharge documents. Because documents cannot be printed on both sides, double-sided printing is more particular than single-sided printing. If the reading order of an open book is from left to right, the left page is called verso in typesetting. The page on the right is called recto (not directly called left page and right page, because for right-to-left reading languages like Arabic or Hebrew, the left page is recto and the right page is verso). Verso is like the only door for readers, subordinate to recto. Recto has the psychological meaning of inviting readers to read and then browsing, suggesting higher importance. Because of this psychological asymmetry, the typesetting of double-sided printed documents must also adapt to this asymmetry, for example, all chapters should start with recto to highlight its importance; Don't have a blank page on the front before the end of the document, otherwise it will imply that the reader will stop here; Page numbers should start from the right, all right pages must be odd and all right pages must be even; Without disturbing the reading order, especially important charts should be placed on the front to highlight their importance. In addition, everyone should have noticed that the page number of the left page is generally in the lower left corner or upper left corner, and the page number of the right page is in the lower right corner or upper right corner. If there is a head, verso's head may be different from recto's. Verso's header uses chapter titles, while recto's header uses section titles. These are also the problems that must be paid attention to in typesetting when printing on both sides.