Formulas need alternative text

PDF/UA check FORMULA_ALT_TEXT · Figures & images · severity Critical · PDF/UA 8.2.5.29.2 Non-mathematical scientific formulae

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Why it matters#

Formulas need text descriptions so blind users understand their meaning. Without alt text, screen readers cannot convey scientific or mathematical content.

What you will see#

A Formula element has no alternative text, so its meaning is unavailable to screen reader users.

How to fix#

Add an Alt or ActualText entry to the Formula structure element giving a textual reading of the formula (e.g. spelling out the chemical or scientific expression). Either entry satisfies the requirement.

Step-by-step guide#

1. Select the flagged Formula tag in the Accessibility tags panel (the EQChecker report gives its page).
2. Open Properties > Tag tab and fill Alternate Text with a spoken reading of the formula, e.g. spell out a chemical equation as words (two Na plus two H two O yields H two plus two Na O H).
3. Or fill Actual Text instead when a literal text replacement reads naturally as text; ISO 14289-2 8.2.5.29.2 accepts either an Alt entry or an ActualText entry.
4. Write descriptions a screen reader can speak unambiguously: spell out operators, subscripts, and Greek letters rather than pasting symbols that may not verbalize.
5. For genuinely mathematical expressions, note that 8.2.5.29.1 additionally requires presentation MathML - as child structure of the Formula or as an Associated File with AFRelationship Supplement. Acrobat cannot author MathML structure; produce it at the source, exporting from an authoring application (for example a LaTeX or Word pipeline) that emits MathML.

Verify: Re-run the EQChecker scan: FORMULA_ALT_TEXT should pass.

Note: The Alt/ActualText SHALL in 8.2.5.29.2 covers non-mathematical scientific formulae such as chemical equations. Mathematical expressions carry the separate MathML requirement in 8.2.5.29.1, so alt text alone does not make math fully PDF/UA-2 conformant - it is still strongly recommended for all formulae as a practical aid.

WCAG success criteria#

1.1.1 Non-text Content — Level A#

All non-text content (images, icons, controls) needs a text alternative that conveys the same purpose, or be marked decorative so assistive tech can ignore it.

Understanding 1.1.1

Standards#

This check contributes to the following standards:

PDF/UA WCAG A EN 301 549