Descriptions are provided for image-based visual content and/or complex structures such as tables, mathematics, diagrams, and charts.


Example 1 — EPUB 3
<meta property="schema:accessibilityFeature">
Example 2 — EPUB 2
<meta name="schema:accessibilityFeature"
Example 3 — Audiobooks
"accessibilityFeature": ["longDescription"]


The longDescription value is used to indicate that all complex content (images, tables, charts, equations, etc.) include an extended description of their purpose.

Complexity is determined by whether alternative text alone is sufficient to convey the full information of the content (e.g., for images and charts), or whether the structure is likely to be understood by someone who cannot see it (e.g., for tables). See the techniques for WCAG success criterion 1.1.1 for more information on when extended descriptions are needed.

See the Image Descriptions knowledge base page for more information.

Long description included in an HTML details element.

<figure id="fig01">
      <p>Figure 1 - Spectral analysis of an earthquake</p>
         <p>The chart shows a typical …</p>

Hidden long description attached using the aria-describedby attribute.

<img src="speheres.jpg" alt="Celestial spheres" aria-describedby="img-desc"/>
<p id="img-desc" hidden="">The 47 spheres are shown …</p>

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