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                                                     411
           SECTION 5.4                                        Introduction to Font Data Structures



           ports two classes of font-related objects, called CIDFonts and CMaps, described in
           Section 5.6.1, “CID-Keyed Fonts Overview.” CIDFonts are listed in Table 5.7 be-
           cause, like fonts, they are collections of glyphs; however, a CIDFont is never used
           directly but only as a component of a Type 0 font.

                                           TABLE 5.7 Font types
TYPE           SUBTYPE VALUE       DESCRIPTION

Type 0         Type0               (PDF 1.2) A composite font—a font composed of glyphs from a descendant
                                   CIDFont (see Section 5.6, “Composite Fonts”)

Type 1         Type1               A font that defines glyph shapes using Type 1 font technology (see Section
                                   5.5.1, “Type 1 Fonts”).

               MMType1             A multiple master font—an extension of the Type 1 font that allows the gen-
                                   eration of a wide variety of typeface styles from a single font (see “Multiple
                                   Master Fonts” on page 416)

Type 3         Type3               A font that defines glyphs with streams of PDF graphics operators (see Sec-
                                   tion 5.5.4, “Type 3 Fonts”)

TrueType       TrueType            A font based on the TrueType font format (see Section 5.5.2, “TrueType
                                   Fonts”)

CIDFont        CIDFontType0        (PDF 1.2) A CIDFont whose glyph descriptions are based on Type 1 font
                                   technology (see Section 5.6.3, “CIDFonts”)

               CIDFontType2        (PDF 1.2) A CIDFont whose glyph descriptions are based on TrueType font
                                   technology (see Section 5.6.3, “CIDFonts”)

           For all font types, the term font dictionary refers to a PDF dictionary containing
           information about the font; likewise, a CIDFont dictionary contains information
           about a CIDFont. Except for Type 3, this dictionary is distinct from the font pro-
           gram that defines the font’s glyphs. That font program may be embedded in the
           PDF file as a stream object or be obtained from some external source.

           Note: This terminology differs from that used in the PostScript language. In Post-
           Script, a font dictionary is a PostScript data structure that is created as a direct re-
           sult of interpreting a font program. In PDF, a font program is always treated as if it
           were a separate file, even if its contents are embedded in the PDF file. The font pro-
           gram is interpreted by a specialized font interpreter when necessary; its contents
           never materialize as PDF objects.

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