1. Page Description Language
2. Escape code language
Page Description Language
As its name describes, page description language (PDL) is a language that describes the appearance of a printed page in a higher level than an actual output bitmap. PDL's are high-level languages that specify the format of a page generated by a printer; they are translated into specific codes by any printer that supports the language. It is generally more versatile and allow more complex pages and graphics to be created. An overlapping term is printer control language. Usually PDL's are used for advance documents such as presentation materials, advertising brochures etc. Page description languages are normally used by software packages which produce sophisticated, highly formatted output, including graphics design programs, advanced word processing packages, spreadsheets with extensive charting capabilities, and desktop publishing packages.
Most commonly used PDL's are:
PDF, Portable Document Format by Adobe
PCL, Printer Command Language by Hewlett-Packard
PostScript Language one of the most noted page description languages, is a fully fledged programming language
Some PDL's are or have been made open standards. There are also other proprietary languages whose details are not publicly disclosed.
Escape code languages
Escape code languages are generally characterized by the structure of the commands they use, each command is prefixed by a special code (normally the escape code, hence the name) to signify that the following characters are a command, and not data to be printed.Printing from a windows application is very easy. Just open the File menu and select “Print” command. Windows operating system can be configured in different way with printer. Currently Novell Netware, PPR. IPP and Email printing are supported by Windows.
Escape code languages are suitable for simple documents and not good for complex pages like graphic design etc. They are less flexible than PDL. Simple documents such as letters, database printouts and document containing simple graphics can be printed with an acceptable printing quality. Most escape code languages do not offer sophisticated typographic features, they can use a range of different fonts but can print text in a limited number of sizes. They also can not handle special effects such as 3 D printing, printing text at an angel etc.
Disadvantages of Page Description Languages
a) Post description languages require a lot of processing power, so PDL printers format data more slowly than ECL printers.
b) PDL printers need more powerfull printer controller, with the result that most PDL printers are more expensive than escape code printers.
c) Some old applications can not use PDL printers. There must be an escape code language built into PDL printers to overcome this problem.
There are other languages which individual printer manufactur use. In some cases the manufacturers provide their own language to use with the printer. Manufacturer also wish to have their language adopted as the industry standard, but in the real world every language has its advantages and disadvantages. Each language has its own role in industry to meet different printing requirments. Sometimes none of these languages fulfils the user requirments so professional programmers are employed to create custom applications supporting unique features.
Kyocera has its own manufacturer specific language. Kyocera uses Kyocera Prescribe in addition to HP PCL emulation. Prescribe is a good language for true type fonts. Mostly it is being used for minicomputer applications and applications using barcodes.
IBM IPDS (Intelligent Printer Data Stream) has more features for IBM mainframe. IBM introduced "Advanced FunctionPrinting" (AFP). AFP is a way in which complex documents can bedescribed on IBM mainframes and minicomputers, and is converted intothe IPDS print language by the operating system on the computer. IPDS does not support other manufacturer's drivers. User must have an IPDS comatible print to print a document. But some printer manufacturers provide IPDS emulation to make PCL or Postscript available to IBM systems. User has to use an external computer to use these emulations which translates IPDS commands into PCL or Postscript.