Generally, modern printing production techniques for publications or documents such as books, magazines, and brochures, can be split into three major stages:                1. Prepress. In the prepress stage of production, documents are prepared for a printing device.        2. Printing. During this stage of production the information produced by the prepress system is duplicated on one or more large sheets of paper called print sheets, using a printing press plate, a digital printing system, or some other duplicator of printed material.        3. Finishing. In this stage the print sheets are folded, assembled and cut to form the final documents.        
In the prepress stage, the individual pages of a document are prepared and ordered according to the page sequence of the final document. The final ordering of the pages is also referred to as the reader order. In order to achieve a desired reader order of the final publication, a pre-printing operation called imposition is required to arrange the individual pages into a layout that is suitable for the media that will ultimately be used to print the pages. Typically, the imposition layout is not in reader order, since the pages must be laid out onto the media with the understanding of how the media will be ultimately folded, cut and stacked in order to produce the final publication. The reader order is only one aspect that the imposition must consider; other considerations are the media size and how the media will be folded, cut and stacked. Imposition arranges the pages on one or more print sheets to achieve a proper sequence or position of each page relative to other pages. Imposition is performed to facilitate post-printing processes by defining the layout of the document's pages so that the pages can be properly imaged onto printing press plates. These plates are then used to print the pages onto one or more print sheets (stage 2, printing), which are later folded, cut and then bound to form the final printed document (stage 3, finishing).
Imposition may be performed manually by an expert familiar with the printing press, its operations, and the distribution of pages in the document, such as a newspaper, in order to design a particular imposition. A particular imposition will depend on several factors and may include, for instance, the editorial content, several different editions, advertisement requirements, and multiple production sites. However, the time available to design an imposition is often short, because changes in page content as dictated by advertising, editorial or fast breaking news stories may occur close to press time. Nevertheless, manually changing an imposition at the last minute can be both time consuming and very expensive because the operator will have to compose a new imposition essentially from scratch.
More often, imposition processes are executed on a computer workstation and assisted by a user, using an imposition software program, such as the Preps™ software by ScenicSoft of Lynnwood, Wash., prior to printing by a printing device. An imposition software program creates an imposition description file that defines how pages are to be arranged and includes all the data required for a printing device to print the print sheet(s). Imposition description files contain user defined image data such as the pages or sub-pages of a document and page layout information for one or more print sheets. For example, a user can define an imposition layout that images four pages (4-up) at a time to a printer. The user may also define the page assignment in a certain way so that when the print sheet is folded and cut, the pages will be in the order defined by the user. Once the print sheets are printed, the print sheets are then folded and cut in accordance with the imposition description file to form one or more segments or signatures of the document which are then combined to form a complete document.
Software-based imposition assignment of one reader order list of pages to an imposition is common practice in the printing industry today. ScenicSoft's Preps™ program provides, either implicitly or explicitly, a means for the user to associate one reader order list of pages to a specific imposition layout. There is a fixed association between the pages of a document and the assignment of those pages to the single imposition layout.