What is PDF/UA? 5 reasons why it matters
Tuesday, May 1, 2012 Return to Logical Structures
PDF provides a reliable and functional electronic document format that serves a number of critical roles in the economy.
There are, however, cases in which traditional untagged PDF performs poorly.
Mobile device users are frustrated by the need to pan around a small screen. Search-engine users notice that PDF files sometimes deliver poor search results or none at all. Those attempting to copy and paste text may encounter a jumble of random characters instead.
For users reading PDF files via assistive technology - screen-readers, joysticks, magnifiers, braille displays and others - the experience is completely unsatisfactory. For these users such problems are more than simply annoying; they represent barriers to the content itself.
First released in 2000, tagged PDF makes it possible to re-use PDF content on mobile devices and with assistive technology such as screen readers and magnifiers.
For a variety of reasons it's taken time for this feature to find broad acceptance. Today, most PDFs are still untagged. Tagged PDFs are frequently substandard, and don't deliver a high-quality experience.
As a consequence, most users who rely on tags in PDF to read have learned to dislike PDF files for the unreliable, disjointed experience they’ve so often received.
The problem goes beyond users who have no choice but to rely on tags. Most search engines do a poor job indexing PDF files because they don't use PDF tags. Mobile devices can’t deliver a high-quality experience when “reflowing” PDF text because the software doesn't understand tags.
Few organizations have made the necessary effort to ensure their PDF files include high quality tags until relatively recently. Few software developers have taken advantage of PDF tags to deliver new features to users.
PDF/UA means "Universally Accessible PDF"
From the Glossary of Accessible PDF
- Logical Order
The sequence of content as consumed by people (ie, words, sentences, paragraphs, etc). Not to be confused with reading order, which should be read as "computer reading order" logical order is critical to accessibility.
- Reading Order
The sequence in which software (as opposed to humans) reads the page in order to display it. The reading order may or may not match the Logical Order, which predominates over mere "reading order" for accessibility purposes.
- Real Content
Text and images required to comprehend the document. Page content that isn't necessary for understanding the document should be marked as an artifact.
Read more from Logical Structures
PDF/UA, a new ISO standard for accessible PDF, sets clear rules for developers and authors of tagged PDF documents and forms.
What does that mean in the real world? There are five big reasons why PDF/UA matters:
- PDF/UA conforming files are a promise from the author to the user that they will enjoy a high-quality reading experience (if they use PDF/UA conforming software).
- PDF/UA conforming creation software will help authors create accessible documents.
- PDF/UA conforming readers for desktop, mobile devices or search engines will be able to offer high quality reflowing, restyling, better search, and more.
- PDF/UA conforming Assistive Technology will be able to offer a top quality experience of PDF to users, including rich, reliable navigation.
- WCAG 2.0 conformance obligations for PDF will be met using PDF/UA-conforming tools. Authors who include movies, scripts and actions in PDF files, require guidance on content or seek Level AAA conformance will need to consult WCAG 2.0 in addition to PDF/UA.
That’s what PDF/UA is all about.