EpubCCEPUBCheck ACC-009: MathML without alt text
Updated:
EPUBCheck ACC-009 is a usage message: “MathML should either have an "alttext" attribute or "annotation-xml" child element.” A MathML equation has no text alternative, neither an alttext attribute nor an annotation-xml element. Screen readers that cannot read MathML then have nothing to say for the equation. It is a usage note shown with -u.
The official message
MathML should either have an "alttext" attribute or "annotation-xml" child element.
- Default severity
- Usage. Informative only and hidden by default: it appears when EPUBCheck runs with -u (--usage). It does not make the EPUB invalid.
- EPUBCheck version
- 5.4.0
Typical causes
- Equations converted to MathML without a text description for screen readers.
- MathML exported from an equation editor that does not write alttext.
How to fix it
- Add alttext to the math element with a readable form of the equation, for example
<math alttext="x squared plus 1">. - Or add an annotation-xml child inside semantics with an alternative representation.
- Check the book with an accessibility checker such as Ace by DAISY for other missing alternatives.
- Rebuild the EPUB and run EPUBCheck again to confirm the message is gone.
When it's not this
If the missing name is on a link inside SVG, the note is ACC-011.
Terms used here
Other ACC messages
ACC-011SVG hyperlink has no accessible name
Sources
Message text and severity from EPUBCheck 5.4.0 (W3C, BSD-3-Clause). Explanation by EpubCC.