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About the contributor
Duff Johnson

A veteran of the electronic document space, Duff Johnson is an independent consultant. He is Executive Director of the PDF Association and ISO Project co-Leader (and US TAG chair) for ISO 32000 and ISO 14289.
More contributions
The Power of the Page

It’s a question that vexes vendors of web-based solutions everywhere: why do people still insist on PDF files? And why does PDF’s mindshare keep going up? “PDF is such antediluvian technology!” they say. “It’s pre-web, are you kidding me? It’s so old-f …

PDF Association technical resources: an overview

PDF is PDF because files produced with one vendor’s software can be read using a different vendor’s software with no loss of fidelity. Interoperability is key to our industry. The PDF Association is a international membership organization dedicated to …

2022: The last year of paper for records-keeping

NARA (The National Archives and Records Administration) is the final depository for the long-term records generated by all other agencies of the U.S. Federal Government. The agency has a key role in preserving the cultural history of the republic as we …

PDF 2.0 examples now available

The PDF Association is proud to present the first PDF 2.0 example files made available to the public. Created and donated to the PDF Association by Datalogics, this initial set of PDF 2.0 examples were crafted by hand and intentionally made simple in construction to serve as teaching tools for learning PDF file structure and syntax.

PDF 2.0 interops help vendors

The PDF 2.0 interop workshops included many vendors with products for creating, editing and processing PDF files. They came together in Boston, Massachusetts for a couple of days to test their own software against 3rd party files.

The Value of Tagged PDF


PDF was originally intended to serve as electronic paper; a properly rendered page irrespective of software or operating system.  Pages, however, aren’t just for reading. Since people like to add notes, draw lines and fill forms, Adobe Systems, the inventors of PDF, decided to cater to these uses as well. PDF rapidly accumulated new features beyond faithfulness to the rendered page – it began to mirror the interactive capabilities of real paper.

The first generation of interactive PDF features consisted of annotations of various types. Some allowed users to add text, others allowed users to draw lines and boxes onto the page. Still others go beyond the paradigm of the page, making it possible to add hyperlinks,  audio and movies to PDF.

The second generation of interactive PDF brought the ability to deploy a PDF’s content outside the page-based world.

Tagged PDF provides the means to effectively deploy a final-form document to a mobile device. It’s the same means by which PDF files may be made accessible to users who requires Assistive Technology (AT) to read.

One of the primary motivations for tagged PDF was to achieve compliance with regulations that require electronic documents to be accessible to users with disabilities, but implementers can leverage tagged PDF to accomplish or enhance a wide range of end user activities.

The following table indicates the utlity of untagged vs. tagged PDF content.

Untagged Content Tagged Content
No semantic types or ordering; content is ordered solely for rendering purposes Semantic type and order is determined, content may be reused accordingly
Search engines cannot reliably access words and phrases Search engines get reliable access to content.
No reliable means of reflowing page content onto smaller devices Includes information necessary for reflow
“Real” content and “artifacts” aren’t distinguished Consuming software can choose to utilize or ignore artifacts
Content copying and extraction is unreliable Content may be extracted with confidence
Not eligible for PDF/A conformance level A May conform with PDF/A conformance level A
Cannot comply with WCAG 2.0 or Section 508 May comply with WCAG 2.0, Section 508 and other accessibility regulations
Inaccessible to disabled users Accessible to those with PDF-aware Assistive Technology

Tags: Section 508, WCAG 2.0, assistive technology, mobile, tags
Categories: PDF, PDF/UA