was also used for other changes to a prepared page, such as a spelling correction, or a stop press story in a newspaper. Digital techniques rendered stripping less necessary, but what has forced increasing numbers to abandon it completely is the introduction of "platesetters", which put pages directly onto printing plates; these plates cannot be adjusted with a sharp knife. In addition, an extremely high precision would be needed for stripping of colour work, as each ink colour is on a separate piece of film. Digital techniques Manual imposition processes tend to cause bottlenecks of the whole printing production. The first digital imposition software, Impostrip, was released in 1989. The advent of digital imposition has not only helped a lot in making sure layout and sheet arrangement are correct with higher register precision, but it significantly reduces the usual imposition errors (e.g., slight movements of register due to parallax). An entire book may be imposed and many complex functions applied in an instant. Binding options may be changed on the fly and impositions produced to multiple output devices at once, often with no user intervention. In turn, digital techniques help to reduce material costs, time and resolves production bottlenecks. There are several different approaches to digital imposition. Imposition in the design application. Software packages that can be used to design single pages can often be used to design entire printed sheets, sometimes by a process as simple as copy/paste onto a larger sheet. This is still in use, especially for low volumes of work, but a popular alternative is an imposition function built in, or added in, to the design tool. This typically takes a document prepared as single pages and creates a new document with full-sheet layouts. This larger layout is then printed to film or a plate. Imposition through shell scripts and operating system features. This approach works particularly well on desktop Unix in a small office/home office environment (where a printer may only be capable of handling A3 and smaller). A trivial script might be written to re-arrange pages in a PostScript or PDF file to make them suitable for final imposition through the built-in Page Setup. For the imposition of an A4-sized hardcover book on A3 paper, for example, one could first write a shell script to re-arrange the document in the following sequence: 1, 32, 31, 2, 3, 30, 29, 4... 33, 64, 63, 34,