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                                         187
SECTION 3.10                                                            File Specifications



well. This is accomplished by including a related files array (PDF 1.3) as the value
of the RF entry in the file specification dictionary. The array has 2 × n elements,
which are paired in the form

   [ string1 stream1
     string2 stream2
     …
     stringn streamn
   ]

The first element of each pair is a string giving the name of one of the related files;
the second element is an embedded file stream holding the file’s contents.

In Example 3.21, objects 21, 31, and 41 are embedded file streams containing the
DOS file SUNSET. EPS, the Mac OS file Sunset . eps, and the UNIX file Sunset . eps,
respectively. The file specification dictionary’s RF entry specifies an array, object
30, identifying a set of embedded files related to the Mac OS file, forming a
DCS 1.0 set. The example shows only the first two embedded file streams in the
set; an actual PDF file would, of course, include all of them.

Example 3.21

   10 0 obj                                % File specification dictionary
      << /Type /Filespec
          /DOS ( SUNSET. EPS)
          /Mac ( Sunset . eps )            % Name of Mac OS file
          /Unix ( Sunset . eps )
          /EF << /DOS 21 0 R
                   /Mac 31 0 R             % Embedded Mac OS file
                   /Unix 41 0 R
              >>
          /RF << /Mac 30 0 R >>            % Related files array for Mac OS file
      >>
   endobj

   30 0 obj                                % Related files array for Mac OS file
      [ ( Sunset . eps ) 31 0 R            % Includes file Sunset . eps itself
        ( Sunset . C ) 32 0 R
        ( Sunset . M ) 33 0 R
        ( Sunset . Y ) 34 0 R
        ( Sunset . K ) 35 0 R
      ]
   endobj

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