Overview: the likely Design of the CUPS filtering system inside Mac OS X (versions from 10.2):
             +--------------------------------------------------+                           +-------------------------------------+    
             |                                                  |                           |                                     |    
             |        Linux-/UNIX application programs          |                           |     Mac OS X prgrams send print     |    
             |        send files to printing subsystem          |                           |     printfiles to Max OS X RIP.. .  |    
             |                                                  |                           |                                     |    
             +--------------------------------------------------+                           +-------------------------------------+    
                    v        v     v     v           v                                                           v                     
                    |        |     |     |           |                                                           |                     
                    V        V     |     V           V                                                           V                     
             +--------+ +--------+ | +-------+ +--------------------+                        ++++++++++++++++++++++++++++++++++++++    
      input  |  Text  | |  PDF   | | | HP/GL | | Image(*)(MIME-Type:|(*)JPEG/JFIF, PNG, GIF  ++++++++++++++++++++++++++++++++++++++    
    formats: |        | |        | | |       | |            image/*)|   SGI-RGB, TIFF, BMP,  ++++++++++++++++++++++++++++++++++++++    
             +--------+ +--------+ | +-------+ +--------------------+   PNM (PBM/PGM/PPM),   +++......._............._..........+++    
                    v        v     |       v    v             v         Sun-Raster,          +++....../_\.._.__._.__| |___......+++    
         pre-  text-|    pdf-|     |  hpgl-|    |             |                              +++...../ _ \| '_ \ '_ \ / -_).....+++    
   filters(*)    to-|     to-|     |    to-|    |             |                              +++..../_/.\_\ .__/ .__/_\___|.....+++    
  (PostScript  ps(*)|   ps(*)|     |  ps(*)|    |             |                              +++..........|_|..|_|..............+++    
  generation):      |        |     |       |    |             |                              +++..___.___..___....___.___.___...+++    
                    V        V     V       V    |             |image-                        +++.| _ \   \| __|__| _ \_ _| _ \..+++    
             +-------------------------------+  |image-       |to-                           +++.|  _/ |) | _|___|   /| ||  _/..+++    
             | POSTSCRIPT (MIME-Type:        |  |to-          |raster(*)                     +++.|_|.|___/|_|....|_|_\___|_|....+++    
             |            application/       |  |ps(*)        |(*)used for non-PostScript    +++................................+++    
             |             postscript)       |  |(*)used      |  printers, based on GS 5.50  +++(will.export.clean."CUPS-Raster"+++    
             +-------------------------------+  | for         |  -- one core element         +++...to.be further.processed by...+++    
                  v                             | PostScript- |  of CUPS-RIP                 +++.....CUPS.Raster.drivers...)....+++    
               ps-|(*)counting                  | printers    |                              +++................................+++    
               to | pages,                      |             |                              +++................................+++    
             ps(*)| accounting,                 |             |                              +++................................+++    
                  | ps-n-up,                    |             |                              +++................................+++    
                  | psselect...                 |             |                              +++................................+++    
                  V                             V             |                              ++++++++++++++++++++++++++++++++++++++    
   +-----------------------------------------------+          |                              ++++++++++++++++++++++++++++++++++++++    
   |     POSTSCRIPT         (MIME-Type:            |  foomatic-rip (a.k.a. "Foomatic")       ++++++++++++++++++++++++++++++++++++++    
   |                        application/           |>- - - - -|- - - - - - - - - - - -+        .(not available      v                  
   |                vnd.cups-postscript)           |          |                       |        . as a standard      |                  
   +-----------------------------------------------+          |                       |        . printpath in       |                  
      v                                v                      |                       |        . Mac OS X)          |                  
      |                                |                      |                       V        v                    |                  
      |             based on        ps-|(*)CUPS-              |       #################################             |                  
      |        GS 5.50 - one        to-| raster               |       #  CUPS-external Ghostscript-   #             |                  
      |         core element  raster(*)| generation           |       #  installation (also poss.:    #             |                  
      |        of CUPS-RIP(*)          | (device              |       #  AFPL Ghostscript 7.04)(*)    #             |                  
      |                                V indep.)              V       #  (*)more than 1.000 models    #             V                  
      |    +----------------------------------------------------------#     supported                 #---------------------------+    
      |    |..___._.._.___..___.....___........._.....................# +-----+ +-----+ +-----+ +---+ #...........................|    
      |    |./ __| || | _ \/ __|___| _ \__ _ __| |_.___._._...........# | gs- | | gs- | | gs- | |   | #..CUPS-Raster..(MIME-Type:.|    
      |    || (__  || |  _/\__ \___|   / _` (_-<  _/ -_) '_|..........# |filter |filter |filter |   | #...............application/|   
      |    |.\___|\__/|_|..|___/...|_|_\__,_|__/\__\___|_|............# | ABC | | XYZ | | 123 | |   | #...........vnd.cups-raster)|    
      |    |............................................. (MIME-Type:.# +-----+ +-----+ +-----+ +---+ #...........................|    
      |    |.............................................application/.#    +-----+ +-----+ +-----+    #...........................|    
      |    |.........................................vnd.cups-raster).#    | gs- | | gs- | | gs- |    #...........................|    
      |    +----------------------------------------------------------#    |filter |filter |filter    #---------------------------+    
      |           v      v       v          v         v       v       #    | abc | | xyz | | 456 |    #                                
    PS-           |      |       |          |         |       |       #    +-----+ +-----+ +-----+    #                                
      -printer     \      \       \          \         \       \      #                               #                                
      |             \      \       \          \         \       \     #################################                                
      |              \      \       \          \         \       \                    v                                                
      |               |      \       \          \         \       \--------+          |                                                
      |        raster-|raster-|raster-|   raster-|  raster-|        raster-|          | committal                                      
      |            to-|    to-|    to-|       to-|      to-|            to-|          | to                                             
      |            pcl|   escp|   dymo| [various]|  printer|     turboprint|          | CUPS-                                          
      |               |       |       |          |         |               |          | backend(*)                                     
      |               V       V       V          V         V               V          | (* determined by                               
      |          +-----+ +-----+ +-----+ 0000000000  #############  #############     |   "device URI")                                
      |          |     | |     | |     | 0        0  #  Gimp-    #  #  Turbo-   #     |                                                
      |   output-|     | |     | |     | 0   ESP  0  #  Print    #  #  Print    #     |                                                
      |  formats:| PCL | |ESC/P| |Dymo | 0  Print 0  # (writes   #  # (writes   #     |                                                
      |          |     | |     | |     | 0   Pro  0  # PCL,ESC/P,#  # PCL,ESC/P,#     |                                                
      |          |     | |     | |     | 0        0  # Canon,etc.#  # Canon,etc.#     |                                                
      |          |     | |     | |     | 0        0  # formats)  #  # formats)  #     |               (c) Kurt Pfeifle,                
      |          +-----+ +-----+ +-----+ 0000000000  #############  #############     |                   Danka Deutschland GmbH       
      |             v         v       v          v         v               v          |                                                
      |             |         |       |          |         |               |          |                                                
      V             V         V       V          V         V               V          V                                                
    *******************************************************************************************************************************    
    *                                                                                                                             *    
    *                      CUPS backends: transfering final printfile & commands to printers                                      *    
    *                                                                                                                             *    
    *----------------------------------------------------+------------------------------------------------------------------------*    
    *           local connections                        |               Network connections                                      *    
    *------------+------------+------------+-------------|------------+--------------+-------------+--------------+---------------*    
    *            |            |            |             |            |              |             | AppSocket/   | NetATalk/     *    
    *  parallel  |  serial    |   USB      |  Firewire   |    IPP     |   LPR/LPD    |  SMB/CIFS   | HP-JetDirect | AppleTalk     *    
    *            |            |            |             |            |              |             |              |               *    
    *******************************************************************************************************************************    
          |      |      |         |      |       |               |      |                    |                 |        |              
          V      V      V         V      V       V               V      V                    V                 V        V              
         +------------+////       +------------+////       +------------+////       +------------+////       +------------+////        
       --|+----------+|///      --|+----------+|///      --|+----------+|///      --|+----------+|///      --|+----------+|///         
       --||   ---    ||//       --||   ---    ||//       --||    ---   ||//       --||   ---    ||//       --||    ---   ||//          
         |+----------+|/          |+----------+|/          |+----------+|/          |+----------+|/          |+----------+|/           
         ||   ---    ||           ||   ---    ||           ||    ---   ||           ||   ---    ||           ||    ---   ||            
         |+----------+|           |+----------+|           |+----------+|           |+----------+|           |+----------+|            
         +------------+           +------------+           +------------+           +------------+           +------------+            
     ..............................................................................................................................    
     ..............................................................................................................................    
     ...                    printers: PostScript, PCL, HP/GL, ESC/P, Tiff   ---  more than 3.000 supported models               ...    
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