A page description language (PDL) is a computer language that describes the appearance of a printed or displayed page in a device-independent manner. Page description languages are used in electronic printing and display environments.
In general, a PDL defines the following:
* A set of graphical elements and their attributes
* A set of page layout rules
* A set of print or display commands
The two most common PDLs used in the book publishing industry are Adobe’s PostScript and Microsoft’s XPS.
When a page is created in a word processing or desktop publishing program, it is generally not created in a PDL. Instead, it is created in a device-dependent format that is specific to the program being used. In order to print or display the page, the program must first convert the page into a PDL. This conversion is generally done by sending the page to a printer or display driver that is capable of understanding the PDL.
Once the page is in a PDL, it can be printed or displayed on any device that supports the PDL. This makes PDLs very important in the publishing industry, where pages must be printed or displayed on a wide variety of devices.
PDLs are also used in some types of eBook readers. In this case, the PDL is used to describe the layout of the pages in the eBook. This allows the eBook reader to display the pages in the same way regardless of the device that is being used.
There are a wide variety of page description languages in use today. Some of the more common PDLs include:
* Adobe PostScript
* Adobe PDF
* Microsoft XPS
PDLs are an important part of the publishing industry. They allow pages to be printed or displayed on a wide variety of devices without the need for conversion. This makes it possible to produce high-quality prints and displays regardless of the device that is being used.