Previous Next

                                                      905
         SECTION 10.7                                                                       Tagged PDF



         The strongly structured paradigm is used by some rich document models based
         on XML. The weakly structured paradigm is typical of documents represented in
         HTML.

         Lists and tables should be organized using the specific structure types described
         under “List Elements” on page 902 and “Table Elements” on page 903. Likewise,
         tables of contents and indexes should be structured as described for the TOC and
         Index structure types under “Grouping Elements” on page 899.


         Inline-Level Structure Elements

         An inline-level structure element (ILSE) contains a portion of text or other content
         having specific styling characteristics or playing a specific role in the document.
         Within a paragraph or other block defined by a containing BLSE, consecutive
         ILSEs—possibly intermixed with other content items that are direct children of
         the parent BLSE—are laid out consecutively in the inline-progression direction
         (left to right in Western writing systems). The resulting content may be broken
         into multiple lines, which in turn are stacked in the block-progression direction.
         It is possible for an ILSE in turn to contain a BLSE, which is treated as a unitary
         item of layout in the inline direction. Table 10.25 lists the standard structure types
         for ILSEs.

                 TABLE 10.25 Standard structure types for inline-level structure elements
STRUCTURE TYPE      DESCRIPTION

Span                (Span) A generic inline portion of text having no particular inherent characteristics. It can
                    be used, for example, to delimit a range of text with a given set of styling attributes.
                    Note: Not all inline style changes need to be identified as a span. Text color and font changes
                    (including modifiers such as bold, italic, and small caps) need not be so marked, since these
                    can be derived from the PDF content (see “Font Characteristics” on page 892). However, it is
                    necessary to use a span to apply explicit layout attributes such as LineHeight, BaselineShift, or
                    TextDecorationType (see “Layout Attributes for ILSEs” on page 926).

                    Note: Marked-content sequences having the tag Span are also used to carry certain accessibil-
                    ity properties (Alt, ActualText, Lang, and E; see Section 10.8, “Accessibility Support”). Such se-
                    quences lack an MCID property and are not associated with any structure element. This use of
                    the Span marked-content tag is distinct from its use as a structure type.

Previous Next