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<textual-form> Textual Form

Textual form provides a place to hold a textual equivalent or searchable textual version of a complex structure such as an equation or a graphical object. The complex object and the textual equivalent are associated with each other by putting them in the same alternatives wrapper.

Usage/Remarks

Display Alternative
One use of the <textual-form> element is inside a display object (such as an equation or figure) to provide an equivalent display alternative for a graphical object. For example, a display equation (<disp-formula>), may be provided in several equivalent, interchangeable forms within an <alternatives> element:
  • as a MathML-encoded equation (<mml:math>),
  • as a plain text alternative which uses ASCII characters and superscripts (<textual-form>), and
  • as a <graphic> such as a tif or jpg.
Similarly, a graphic can be provided with a simpler (as opposed to equivalent) alternative form, to provide gentle degradation for hardware that cannot process the media or graphical object.
Special Characters
The <textual-form> element can also be used to supply a textual or Unicode description of a special character that is being defined using a <private-char> element, as an alternative to bitmaps or graphics. For example, an <alternatives> element could be used to hold multiple ways of defining the character:
  • one or more graphics (<inline-graphic>),
  • one or more bitmaps (<glyph-data> bitmap inside <private-char> element), and
  • as one or more textual alternatives (<textual-form>) to name alternative characters in the Unicode Standard that can be used to create a visual approximation of the character being defined.
Search Text
The <textual-form> element can also be used to hold the text of an object for searching. In such a usage, it is not intended that the <textual-form> be displayed to the user, only that it provide a textual view of the object to a search system. This technique can allow unsearchable binary formats, such as graphics and untagged tables represented as graphics, to be represented in a form that can be searched or indexed.
Attributes
specific-use

Multi-lang Attributes

lang-focus
lang-focus-custom
lang-group
lang-source
lang-source-custom
lang-translate
lang-variant
lang-variant-custom

Base Attributes

id
xml:base
xml:lang
Models and Context
May be contained in
<alternatives>, <chem-struct-wrap>
Description
Any combination of:
Content Model
<!ELEMENT  textual-form (#PCDATA %textual-form-elements;)*           >
Expanded Content Model

(#PCDATA | bold | fixed-case | italic | monospace | overline | roman | sans-serif | sc | strike | underline | ruby | inline-graphic | inline-media | private-char | mml:math | named-content | styled-content | sub | sup)*

Tagged Samples
Formula (graphic, MathML, textual form) 
...
<disp-formula>
 <alternatives>

  <textual-form>(a + 3)<sup>2</sup> - (10 - b) = 24</textual-form>

  <graphic xmlns:xlink="http://www.w3.org/1999/xlink"
    xlink:href="fors2682.f3">
   <object-id>463492</object-id>
  </graphic>

  <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
   <mml:mrow>
    <mml:msup>
     <mml:mfenced>
      <mml:mrow>
       <mml:mi>a</mml:mi>
       <mml:mo>&plus;</mml:mo>
       <mml:mn>3</mml:mn>
      </mml:mrow>
     </mml:mfenced>
     <mml:mn>2</mml:mn>
    </mml:msup>
    <mml:mo>&minus;</mml:mo>
    <mml:mfenced>
     <mml:mrow>
      <mml:mi>10</mml:mi>
      <mml:mo>&minus;</mml:mo>
      <mml:mn>b</mml:mn>
     </mml:mrow>
    </mml:mfenced>
    <mml:mo>&equals;</mml:mo>
    <mml:mn>24</mml:mn>
   </mml:mrow>
  </mml:math>

 </alternatives>
</disp-formula>
...
Triple bond glyph
To a chemist, a triple bond is not the same character as Unicode x2261, but <alternatives> may be used to display the triple bond visually and still stay within Unicode. 
...
<alternatives>

 <textual-form specific-use="unicode-look-alike">≡</textual-form>

 <private-char name="Triple Bond" description="Chemistry Triple Bond">
  <glyph-data id="tbond" format="PBM" resolution="300"
    x-size="16" y-size="32">
   0000000000000000000000000000000
   0000000000000000000000000000000
   0000000000000000000000000000000
   0000000000000000000000000000000
   0000000000000000000000000000000
   0001111111111111111111111100000
   0000000000000000000000000000000
   0000000000000000000000000000000
   0001111111111111111111111100000
   0000000000000000000000000000000
   0000000000000000000000000000000
   0001111111111111111111111100000
   0000000000000000000000000000000
   0000000000000000000000000000000
   0000000000000000000000000000000
   0000000000000000000000000000000
   0000000000000000000000000000000
   0000000000000000000000000000000
  </glyph-data>
 </private-char>

</alternatives>
...
Text-dump of a table
The text of the table is available for searching and indexing
...
<table-wrap id="tbl-3">
 <caption>
  <title>Categories of Color Immediacy</title>
 </caption>
 <alternatives>
  <graphic id="tbl3-jpg"
    xlink:href="immediacy-tab3.jpg"/>
  <textual-form specific-use="search/index">
   Description of Color Category
   Number of Immediacy Events

   1. Drew parallels between green and blue relationships
   21 events

   2. Encouraged expression of yellow feelings
   12 events

   3. Admitted red termination
   8 events
   ...

   Note. These results are based on 44 immediacy events.
   Categories were not mutually exclusive, and several types
   of immediacy may occur in each event. Each category was
   recorded only once per event.
  </textual-form>
 </alternatives>
</table-wrap>
...