Postscript: A FORTH like page description language that allows printer operations to be built up from a simple set of basic operations. Each Postscript printout is -- in effect -- a Postscript program whose purpose is to print the desired page(s). Postscript is widely used by Apple and Linux where the open source equivalent is Ghostscript. It is used by PCs, but not as widely. There are standards for structuring Postscript documents -- notably Adobe Document Structuring Convention (DSC). However many commonly used document sources including Microsoft Word are not DSC compliant.

Advantages of Postscript include portability and the ability to describe elaborate formats. If a page includes repeated operations the Postscript representation may be substantially smaller than alternative print files.

Drawbacks include poor speed in some implementations, inability of many Postscript printers to handle simple ASCII without translation software; the existence of incompatible dialects of Postscript, and the fact that as a program, errors in generation or dialect differences can cause the printer to loop endlessly generating garbage or doing nothing at all.

Postscript can be used as a device independent means of transmitting a document. It can be difficult to determine how many pages are in a postscript file or what material is on what page except by printing or viewing the file. It is possible to edit a postscript page but the page generally can not be converted back to a standard word processing format.

Encapsulated Postscript is a restricted subset of Postscript intended to convey pictures or similar material between postscript and postscript even some non-postscript programs. Encapsulated Postscript files may contain alternate representations of material such as TIFF. They generally have an EPS extension.

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