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                                                     907
          SECTION 10.7                                                                   Tagged PDF



STRUCTURE TYPE      DESCRIPTION

Ruby                (Ruby; PDF 1.5) A side-note (annotation) written in a smaller text size and placed adjacent
                    to the base text to which it refers. It is used in Japanese and Chinese to describe the pro-
                    nunciation of unusual words or to describe such items as abbreviations and logos. A Ruby
                    element may also contain the RB, RT, and RP elements. See “Ruby and Warichu Elements”
                    on page 910 for more details.

Warichu             (Warichu; PDF 1.5) A comment or annotation in a smaller text size and formatted onto
                    two smaller lines within the height of the containing text line and placed following (inline)
                    the base text to which it refers. It is used in Japanese for descriptive comments and for ruby
                    annotation text that is too long to be aesthetically formatted as a ruby. A Warichu element
                    may also contain the WT and WP elements. See “Ruby and Warichu Elements” on page 910
                    for more details.


          Link Elements

          Link annotations (like all PDF annotations) are associated with a geometric
          region of the page rather than with a particular object in its content stream. Any
          connection between the link and the content is based solely on visual appearance
          rather than on an explicitly specified association. For this reason, link annota-
          tions alone are not useful to users with visual impairments or to applications
          needing to determine which content can be activated to invoke a hypertext link.

          Tagged PDF link elements (structure type Link) use PDF’s logical structure facili-
          ties to establish the association between content items and link annotations, pro-
          viding functionality comparable to HTML hypertext links. The following items
          can be children of a link element:

          • One or more content items or other ILSEs (except other links)
          • Object references (see “PDF Objects as Content Items” on page 868) to one or
            more link annotations associated with the content

          A link element may contain several link annotations if the geometry of the
          content requires it. For instance, if a span of text wraps from the end of one line to
          the beginning of another, separate link annotations may be needed to cover the
          two portions of text. All of the child link annotations must have the same target
          and action. To maintain a geometric association between the content and the an-
          notation that is consistent with the logical association, all of the link element’s
          content must be covered by the union of its child link annotations.

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