The $mediaobject-accessibility parameter determines how accessibility features are added to media objects (image, video, and audio elements).

The value of this parameter is a list of strings. If the list contains:

summary

A summary attribute will be added if there is an alt element or a textobject containing a single phrase is available.

details

A details element will be added to the div that surrounds the image if there is a textobject containing anything other than a single phrase available.

The list may contain either or both values. If other values are present, they are ignored.

See Example 1.1, An example of media object accessibility.

   |<mediaobject>
   |   <alt>This is a skeuomorphic “postage stamp” with the
   |DocBook logo.</alt>
   |   <imageobject>
   |      <imagedata fileref="media/stamp400x256.png"/>
   |   </imageobject>
   |   <textobject>
   |      <para>This is a skeuomorphic image of a “postage
   |stamp.” Centrally, it features the DocBook wood
   |duck logo. the word “DocBook” appears on the left
   |hand side, rotated 90° counter-clockwise. The
   |DocBook tag line, “The Source for Documentation”
   |is printed in the upper-right corner.
   |</para>
   |   </textobject>
   |</mediaobject>

One possible rendering of such an example:

This is a skeuomorphic image of a “postage stamp.” Centrally, it features the DocBook wood duck logo. the word “DocBook” appears on the left hand side, rotated 90° counter-clockwise. The DocBook tag line, “The Source for Documentation” is printed in the upper-right corner.

Inspection of the HTML will reveal that the summary attribute is present on the div that wraps the figure and a details element precedes the image. These may or may not be rendered by your user agent depending on its accessibility features and settings.

See also $table-accessibility.