ال بي بي دي PostScript Printer Description هو تعريف طابعة تعريف طابعة PostScript و غالبا بتكون خاصة بماكينات الفرز أو السي تي بي فهو يحتوي على معلومات عن جهاز المخرجات بما في ذلك الخطوط الموجودة في الطابعة،
A CUPS PostScript printer driver consists of a PostScript Printer Description (PPD) file that describes the features and capabilities of the device, zero or more filter programs that prepare print data for the device, and zero or more support files for color management, online help, and so forth. The PPD file includes references to all of the filters and support files used by the driver.
Every time a user prints something the scheduler program, determines the format of the print job and the programs required to convert that job into something the printer understands. CUPS includes filter programs for many common formats, for example to convert Portable Document Format (PDF) files into device-independent PostScript, and then from device-independent PostScript to device-dependent PostScript. Photo 1 shows the data flow of a typical print job.
The optional PostScript filter can be provided to add printer-specific commands to the PostScript output that cannot be represented in the PPD file or to reorganize the output for special printer features. Typically this is used to support advanced job management or finishing functions on the printer. CUPS includes a generic PostScript filter that handles all PPD-defined commands.
The optional port monitor handles interface-specific protocol or encoding issues. For example, many PostScript printers support the Binary Communications Protocol (BCP) and Tagged Binary Communications Protocol (TBCP) to allow applications to print 8-bit (“binary”) PostScript jobs. CUPS includes port monitors for BCP and TBCP, and you can supply your own port monitors as needed.
The backend handles communications with the printer, sending print data from the last filter to the printer and relaying back-channel data from the printer to the upstream filters. CUPS includes backend programs for common direct-connect interfaces and network protocols, and you can provide your own backend to support custom interfaces and protocols.
The scheduler also supports a special “command” file format for sending maintenance commands and status queries to a printer or printer driver. Command print jobs typically use a single command filter program defined in the PPD file to generate the appropriate printer commands and handle any responses from the printer. Photo 2 shows the data flow of a typical command job.