Checks

Accessibility

Why accessible PDFs now matter for theses and papers, what tagged PDF and PDF/UA mean, how the Overfull templates produce them, how to write alt text, how veraPDF fits in, and what still needs a human check.

An accessible PDF can be read with a screen reader, reflowed, searched and navigated by structure. For a long time LaTeX could not produce one without heavy manual work. That has changed, and so have the rules.

Why it matters now

  • European Accessibility Act. Applies since 28 June 2025 to many digital products and services sold in the EU, including e-books (European Commission). Publishers have been updating their requirements as a result.
  • ADA Title II (United States). A 2024 Department of Justice rule requires state and local governments, including public universities, to make the web content and documents they provide meet WCAG 2.1 AA. An interim final rule published in the Federal Register on 20 April 2026 moved the compliance dates to 26 April 2027 for entities serving 50,000 people or more, and to 26 April 2028 for smaller entities and special districts. The standard did not change (Federal Register, interim final rule; summary by Parker Poe). This is not legal advice; ask your institution how it applies to you.
  • Universities. Many universities already require accessible theses; check your graduate school. See, for example, the University of Utah’s thesis accessibility guidance.

Accessibility also helps readers who are not disabled: text that copies correctly, a PDF that reflows on a phone, figures that are described.

Tagged PDF and PDF/UA

A tagged PDF contains a structure tree next to the visible page: headings, paragraphs, lists, tables, figures with alternative text, and the reading order. Assistive technology reads the tree, not the page layout.

PDF/UA (ISO 14289) is the standard for accessible PDF. PDF/UA-1 is based on PDF 1.7. PDF/UA-2 (2024) is based on PDF 2.0. Both require a tagged PDF, a document language, a title, alt text for figures, and more.

How the templates do it

The thesis and paper templates use the LaTeX team’s built-in tagging support, compiled with LuaLaTeX. The first command of main.tex is a \DocumentMetadata declaration along these lines (the real one also sets pdfversion=2.0, and in the paper template a MathML setup for LuaLaTeX):

\DocumentMetadata{lang=en, pdfstandard=ua-2, tagging=on}

The slides template cannot do this: Beamer slides cannot be tagged yet. Its overfull.yml leaves out the accessibility check. Share the thesis or paper PDF with the slides, or move to the ltx-talk class.

On top of that, the templates:

  • set the document title and language and show the title in the viewer;
  • give every sample figure alt text;
  • use real tables with header rows and real math;
  • use packages known to work with tagging.

CI for the thesis and paper templates requires them to pass overfull check, including veraPDF’s PDF/UA validation. Keep that line when you edit the template. If you add a package that breaks tagging, the accessibility check will show it.

Alt text

Alt text replaces the figure for someone who cannot see it. Write what the reader should learn, in one to three sentences. Do not repeat the caption.

\includegraphics[width=\linewidth,
  alt={Line chart: training loss falls from 2.1 to 0.4 over 50 epochs and is flat after epoch 30.}]
  {figures/loss.pdf}
Weak Better
“Figure 3” “Bar chart: our method reaches 81% accuracy, the baseline 60%.”
“Diagram of the system” “Pipeline: documents are split into chunks, embedded, indexed, then retrieved for each query.”
“Photo” “Prototype sensor board, about the size of a credit card, mounted on a drone arm.”
A paragraph listing every data point The trend and the values the text relies on. Put full data in a table.

For complex figures, describe the main point in the alt text and give the details in the text or a table.

veraPDF

veraPDF is the open-source reference validator for PDF/A and PDF/UA. The Overfull Docker image includes it, and the template workflow runs it on every build. overfull check runs it whenever verapdf is on the PATH (PDF/UA-2, falling back to PDF/UA-1 for older PDFs) unless you pass --no-verapdf. Its failures appear in the accessibility check as verapdf-<clause> rules, for example verapdf-8-2-5-26. overfull explain <rule> gives a plain-language explanation.

Without veraPDF (for example in the browser check, or with the CLI on a machine where veraPDF is not installed), Overfull still checks the basics: tagging (pdf-not-tagged), language (pdf-missing-language), title (pdf-missing-title), figures without alt text (figure-missing-alt), embedded fonts (font-not-embedded) and the PDF/UA claim (pdfua-not-claimed). It reports verapdf-not-run so you know the full validation did not happen. That is info in the browser check, in the GitHub Action and on a machine with neither veraPDF nor Docker. It is a warning only when the CLI could have run veraPDF through Docker and the profile requires accessibility (thesis, paper). Full PDF/UA validation runs in overfull check with veraPDF or Docker, and in the template workflow.

What automation cannot check

A PDF can pass veraPDF and still be hard to use. Before you submit, check by hand:

  • Alt text is accurate and useful, not just present.
  • Reading order is right in multi-column layouts and around floats.
  • Headings follow the document structure without skipped levels.
  • Link text makes sense on its own (“the dataset documentation”, not “here”).
  • Colour is not the only way information is shown in figures, and contrast is sufficient.
  • Tables used for data have headers; no tables are used for layout.
  • Open the PDF with a screen reader (NVDA on Windows, VoiceOver on macOS) and listen to the first pages and one figure.

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