In prepress and printing, an imposition or layout in which a printing plate containing both the front and back of a sheet are mounted on the press at the same time and print on a double-size sheet of paper. Thus, half the sheet is the top printing, while the other half of the sheet is the "back printing." When half the required number of sheets have been printed, the printed sheets are flipped over (keeping the same gripper edge) and run through again. This will result in the respective back printing on both halves of the sheet. After cutting the printed sheets in half, the job will be done, and it required half the number of impressions that would have been required with standard one-up printing. See also Work-and-Tumble and Work-and-Twist.
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