The positioning of pages on a press sheet in such a manner that when the sheet is folded into a signature and cut, the pages will be in the correct sequence. Imposition involves not just the correct positioning of pages on the same side of the sheet, but also the back printing, or the pages printed on the back of the sheet. Back-printed pages can be oriented in a variety of ways; head-to-head imposition involves aligning the back printing so that the top of the page on the front is opposite the top of the page on the reverse; head-to-foot imposition involves aligning the back printing such that the top of the page on the front is opposite the bottom of the page on the reverse; head-to-side imposition involves back printing that is at a right angle to the printing on the front. Coming-and-going imposition is a type of page sequencing in which the recto (or right-hand) pages are in numerical sequence from the front of the book to the back, but the verso (or left-hand) pages are sequenced such that when the book is flipped over, they are then in sequence from the back of the book to the front.
Based on the size of the press and the press sheets to be used for a particular print job, film negatives or positives of pages are stripped into the proper imposition during the film assembly stage of prepress. Newer digital prepress processes also allow the output of properly-imposed pages as film negatives directly from an imagesetter. (See also Stripping, PrePress: Graphic Arts Photography and Flat Assembly, and Prepress: Digital Prepress.)