What is PDF/UA?
PDF/UA (ISO 14289) is the standard for PDFs that work with screen readers and assistive technology. Drop a file for a free structural scorecard — no signup.
ISO 14289 · Preflight's Accessibility module runs the PDF/UA-1 (ISO 14289-1) rule pack + WCAG 2.2, Section 508, EN 301 549. PDF/UA-2 (ISO 14289-2, PDF 2.0) facets are recognized but not yet fully evaluated — reported not-evaluable, never an invented pass.
PDF/UA (“Universal Accessibility”) specifies what a PDF needs to deliver a consistent, high-quality reading experience through assistive technology. The mechanism is tagged PDF: a logical structure tree that labels every piece of real content — headings, paragraphs, lists, tables, figures — in the correct reading order, with alternative text for images and a declared document language. Conformance is tested with the Matterhorn Protocol (31 checkpoints, 136 failure conditions; 87 software-checkable, 47 human-judgment).
How to make a PDF/UA-compliant file
- Start from a tagged source — author with real styles (headings, lists, tables) so structure exports as tags, not loose text.
- Set reading order and alt text — verify the tag tree matches the visual order and add alternative text to every meaningful image.
- Declare language and title — set the document language and a descriptive title, and show the title rather than the filename.
- Mark artifacts — tag decorative elements, running headers/footers, and backgrounds as artifacts so assistive tech skips them.
- Validate, then review by hand — run a machine check for the 87 automatable Matterhorn conditions, then have a person confirm the 47 that need human judgment.
Frequently asked questions
Is PDF/UA the same as WCAG?
They are complementary. WCAG is the web-wide accessibility guideline; PDF/UA is the file-format standard that defines how a PDF meets those goals via tagged structure. Preflight checks both, plus Section 508 and EN 301 549.
What is tagged PDF?
A hidden logical structure tree that labels headings, paragraphs, lists, tables, and figures in reading order, so assistive technology can interpret the document correctly.
What is the difference between PDF/UA-1 and PDF/UA-2?
PDF/UA-1 (ISO 14289-1:2014) is based on PDF 1.7; PDF/UA-2 (ISO 14289-2:2024) is based on PDF 2.0 and aligns with modern well-tagged PDF practice. Preflight runs the PDF/UA-1 mandatory rule pack today; PDF/UA-2-specific facets that depend on PDF 2.0 structures are not yet fully evaluated — those conditions are reported not-evaluable rather than passed.
What is the Matterhorn Protocol?
A free PDF Association testing model of 31 checkpoints and 136 failure conditions for PDF/UA; 87 are software-checkable and 47 require human review. Preflight automates the machine-checkable conditions and flags the rest rather than guessing.
Can a file be both PDF/A and PDF/UA?
Yes, and it is common for archiving — pair PDF/A-2 or A-3 with PDF/UA-1 (PDF 1.7), or PDF/A-4 with PDF/UA-2 (PDF 2.0). Preflight checks PDF/A conformance and the PDF/UA-1 accessibility rule pack.