Textual descriptions of math equations are included, whether in the alt attribute for image-based equations, using the alttext attribute for [MathML] equations, or by other means.


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


The describedMath value is used to indicate that a publication includes textual descriptions for math equations.

Text descriptions can be provided, for example, using language-specific technologies like the MathML alttext attribute. They can also be provided using the HTML alt attribute when only images are used. The value is a human readable equivalent.

Math description provided in an alttext attribute.

<math xmlns="" display="inline"
      alttext="(mathml alt-text): y minus y 1 equals StartFraction y 2 minus y 1 Over x 2 minus x 1 EndFraction left-parenthesis x minus x 1 right-parenthesis">

This property is complementary to the MathML and latex properties, as the inclusion of either MathML- or latex-formatted equations does not infer that text descriptions will be available.

Related Links