Accessibility Guide
Purpose: Use this reference when the output must meet PDF/UA or WCAG requirements, or when alt text, reading order, contrast, or tagged PDF support matters.
Contents
- Standards overview
- Tagged PDF creation
- Alt text and reading order
- Contrast and font rules
- Testing tools
- Accessible conversion checklist
Standards Overview
PDF/UA
Key requirements:
- Tagged PDF structure
- Logical reading order
- Alternative text for meaningful images
- Document language metadata
- Unicode text
- Title and document metadata
WCAG 2.1
Key criteria used here:
| Criterion | Level | Requirement |
|---|---|---|
| Non-text content | A | Alt text for images |
| Structure and relationships | A | Headings, lists, and tables are programmatic |
| Meaningful sequence | A | Reading order is logical |
| Contrast | AA | 4.5:1 minimum for normal text |
| Page titled | A | Document title exists |
| Language of page | A | Language metadata exists |
Tagged PDF Creation
# Basic tagged PDF
pandoc input.md -o output.pdf \
--pdf-engine=xelatex \
-V classoption=tagged \
--metadata lang=ja \
--metadata title="Document Title"
# Full accessibility-oriented PDF
pandoc input.md -o output.pdf \
--pdf-engine=lualatex \
-V documentclass=article \
-V classoption=tagged \
--metadata lang=ja \
--metadata title="Document Title" \
--metadata author="Author Name" \
-V fontsize=12pt \
-V geometry="margin=25mm" \
--toc --toc-depth=3Rules:
- Minimum accessible PDF font size:
12pt. - Language metadata is required.
- Use tagged output when the document must be accessible.
Alt Text And Reading Order
- Provide meaningful alt text for informative images.
- Mark decorative images as artifacts when the toolchain supports it.
- Verify reading order with extracted text and manual review.
pdftotext -layout output.pdf -Contrast And Font Rules
| Item | Requirement |
|---|---|
| Normal text | 4.5:1 |
| Large text | 3:1 minimum practical target; 4.5:1 is acceptable for stricter policies |
| Accessible PDF font size | 12pt minimum |
Testing Tools
| Tool | Use |
|---|---|
| PAC 3 | PDF accessibility scan |
pdfinfo |
metadata and tagged status |
pdftotext |
reading order review |
pdffonts |
font embedding check |
Example:
pdfinfo output.pdf
pdftotext -layout output.pdf -
pdffonts output.pdfAccessible Conversion Checklist
- Tagged PDF generated
- Language metadata present
- Title metadata present
- Alt text reviewed
- Reading order reviewed
- Contrast meets
4.5:1 - Font size
>= 12pt - Automated scan completed
- Manual review completed