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                                                  449
          SECTION 5.6                                                            Composite Fonts



KEY              TYPE          VALUE

WMode            integer       (Optional) A code that determines the writing mode for any CIDFont with
                               which this CMap is combined. The possible values are 0 for horizontal and 1
                               for vertical. Default value: 0.
                               The value of this entry should be the same as the value of WMode in the
                               CMap file.

UseCMap          name or       (Optional) The name of a predefined CMap, or a stream containing a CMap,
                 stream        that is to be used as the base for this CMap. This base allows the CMap to be
                               defined differentially, specifying only the character mappings that differ from
                               the base CMap.


          CMap Example and Operator Summary

          CMap files are fully documented in Adobe Technical Note #5014, Adobe CMap
          and CIDFont Files Specification. The following example of a CMap stream object
          illustrates and partially explains the contents of a CMap file. There are several
          reasons for including this material here:

          • It documents some restrictions on the contents of a CMap file that can be
            embedded in a PDF file.
          • It provides background to aid in understanding subsequent material, particu-
            larly “CMap Mapping” on page 453.
          • It is the basis for a PDF feature, the ToUnicode CMap, which is a minor exten-
            sion of the CMap file format. This extension is described in Section 5.9,
            “Extraction of Text Content.”

          Example 5.10 is a sample CMap for a Japanese Shift-JIS encoding. Character
          codes in this encoding can be either 1 or 2 bytes in length. This CMap could be
          used with a CIDFont that uses the same CID ordering as specified in the
          CIDSystemInfo entry. Note that several of the entries in the stream dictionary are
          also replicated in the stream data.

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