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          SECTION 5.5                                                                  Simple Fonts




                              TABLE 5.11 Entries in an encoding dictionary
KEY                 TYPE      VALUE

Type                name      (Optional) The type of PDF object that this dictionary describes; if present, must
                              be Encoding for an encoding dictionary.

BaseEncoding        name      (Optional) The base encoding—that is, the encoding from which the Differences
                              entry (if present) describes differences—specified as the name of a predefined
                              encoding MacRomanEncoding, MacExpertEncoding, or WinAnsiEncoding (see
                              Appendix D).
                              If this entry is absent, the Differences entry describes differences from an im-
                              plicit base encoding. For a font program that is embedded in the PDF file, the
                              implicit base encoding is the font program’s built-in encoding, as described
                              above and further elaborated in the sections on specific font types below. Other-
                              wise, for a nonsymbolic font, it is StandardEncoding, and for a symbolic font, it
                              is the font’s built-in encoding.

Differences         array     (Optional; not recommended with TrueType fonts) An array describing the differ-
                              ences from the encoding specified by BaseEncoding or, if BaseEncoding is ab-
                              sent, from an implicit base encoding. The Differences array is described below.

          The value of the Differences entry is an array of character codes and character
          names organized as follows:

               code1 name1,1 name1,2 …
               code2 name2,1 name2,2 …
               …
               coden namen,1 namen,2 …

          Each code is the first index in a sequence of character codes to be changed. The
          first character name after the code becomes the name corresponding to that code.
          Subsequent names replace consecutive code indices until the next code appears
          in the array or the array ends. These sequences may be specified in any order but
          should not overlap.

          For example, in the encoding dictionary in Example 5.9, the name quotesingle ( ' )
          is associated with character code 39, Adieresis (Ä) with code 128, Aring (Å) with
          129, and trademark (™) with 170.

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