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           SECTION 5.6                                                            Composite Fonts



           In PDF, the CMap and CIDFont are represented by PDF objects, which are de-
           scribed below. The CMap and CIDFont programs themselves can be either refer-
           enced by name or embedded as stream objects in the PDF file. As stated earlier,
           the external file formats are documented in Adobe Technical Note #5014, Adobe
           CMap and CIDFont Files Specification.

           A CID-keyed font, then, is the combination of a CMap with a CIDFont contain-
           ing glyph descriptions. It is represented as a Type 0 font. It contains an Encoding
           entry whose value is a CMap dictionary, and its DescendantFonts entry refer-
           ences the CIDFont dictionary with which the CMap has been combined.


  5.6.2 CIDSystemInfo Dictionaries

           CIDFont and CMap dictionaries contain a CIDSystemInfo entry specifying the
           character collection assumed by the CIDFont associated with the CMap—that is,
           the interpretation of the CID numbers used by the CIDFont. A character collec-
           tion is uniquely identified by the Registry, Ordering, and Supplement entries in
           the CIDSystemInfo dictionary, as described in Table 5.13. Character collections
           whose Registry and Ordering values are the same are compatible.

           The CIDSystemInfo entry in a CIDFont is a dictionary that specifies the
           CIDFont’s character collection. The CIDFont need not contain glyph descriptions
           for all the CIDs in a collection; it can contain a subset. The CIDSystemInfo entry
           in a CMap is either a single dictionary or an array of dictionaries, depending on
           whether it associates codes with a single character collection or with multiple
           character collections; see Section 5.6.4, “CMaps.”

           For proper behavior, the CIDSystemInfo entry of a CMap should be compatible
           with that of the CIDFont or CIDFonts with which it is used. If they are incompat-
           ible, the effects produced are unpredictable.

                            TABLE 5.13 Entries in a CIDSystemInfo dictionary
KEY             TYPE        VALUE

Registry        ASCII       (Required) A string identifying the issuer of the character collection—for example,
                string      Adobe. For information about assigning a registry identifier, contact the Adobe
                            Solutions Network or consult the ASN Web site (see the Bibliography).

Ordering        ASCII       (Required) A string that uniquely names the character collection within the speci-
                string      fied registry—for example, Japan1.

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