CommonLook Clarity powered by CommonLook logo

CommonLook PDF powered by CommonLook logo.

CommonLook Office powered by CommonLook logo.

CommonLook Service powered by CommonLook logo.

CommonLook Train powered by CommonLook logo.


Recent Posts

Why Should Enterprise Organizations Care About PDF Accessibility
Wednesday, March 19, 2014
2014 is shaping up to be an important year in the efforts to ensure that web sites are accessible. Learn why businesses big and small should care about PDF Accessibility.

Checking Logical Reading Order with CommonLook PDF
Monday, June 24, 2013
If paragraphs, tables, headings and lists are jumbled together their content is inaccessible; in PDF this can happen all too often.

The Library of Congress Prefers PDF/UA for WCAG 2.0 compliance in archival content
Wednesday, May 29, 2013
The Sustainability of Digital Formats project names PDF/UA as preferred to PDF/A alone for archiving accessible electronic documents.

In business? Your attorney wants you to think about accessibility
Monday, April 22, 2013
The ADA is coming to your website and other customer and employee communications. What are you doing about it?

Department of Education's Office for Civil Rights Conducts Accessibility Compliance Review
Thursday, April 4, 2013
The U.S. Dept. of Education and South Carolina Technical College System (SCTCS) agreed to ensure that SCTCS websites and its 16-member colleges are accessible to persons with disabilities.

Blog Archives

Connect with Us

Facebook follow icon.

For Email Marketing you can trust


Sites of Interest

The Section 508 Refresh Takes a Far Too Expansive View of WCAG 2.0

Do the Web Content Accessibility Guidelines 2.0 really apply to "all electronic content?" Is it really the government's job to say when something is "straightforward"?
netcentric content

Tuesday, March 6, 2012  Return to Logical Structures

While applauding the approach taken by the U.S. Access Board in choosing to reference established technical accessibility standards in their December 2011 ANPRM, I feel compelled to register my deep concern regarding the implementation of these regulations in the PDF context, and likely other non-web contexts as well.

Please file your own comment!

I encourage other members of electronic content industries (all of whom are affected, it seems) to make their own voices be heard by filing a comment at the website. My own comment, complete with proposed new wording for the regulations, will go in before the close of the comment period on March 7, 2012. If you agree with me (and if you don't), please feel free to leave a (preferably signed) comment on this page.

What's the Problem, Duff!

What's the problem, you ask? The following paragraph occurs in the Access Board's December 2011 ANPRM (Advance Notice of Proposed Rule Making) on the Section 508 Refresh in Advisory E205.1 and Advisory C203.1. (link to the ANPRM):

"WCAG is written to be technology neutral.  While oriented towards web pages which are defined as being delivered using HTTP, it is straightforward to apply the WCAG 2.0 Success Criteria and Conformance Requirements to all electronic content." (emphasis added)

I have two main observations.

  1. Minimally, the Access Board's alteration of WCAG 2.0's scope from "web content" to “all electronic content” is a dramatic expansion of WCAG 2.0's stated purpose.
  2. Who is the U.S. Access Board (or W3C, for that matter) to determine that applying WCAG 2.0 to “all electronic content” is "straightforward", and how did they arrive at this astonishing conclusion?

Scope Bloat

There's little question that WCAG 2.0 was not written with the intent of addressing "all electronic content" - the name of the standard itself is a bit of a giveaway. The phrase (and notion) "web page" suffuses the document. Had the authors actually intended WCAG 2.0 to cover all electronic content it's safe to say that the Guidelines would have received very different inputs from the Committee's more technically inclined participants.

WCAG 2.0's four Principles are indeed probably general and valid for all electronic content, but if WCAG 2.0 had actually been designed with "all content" in mind it would be, quite frankly, a completely different document, certainly at the Success Criteria level. Who knows? That's not the road W3C took when it developed the Guidelines.

Straightforward? Really?

PDF file icon with "WCAG 2.0?".By stating that WCAG 2.0 is straightforward to apply to "all electronic content", the Access Board has made an extremely general statement covering a wide range of technologies. Perhaps such application is straightforward for some, but is it really “straightforward” to apply WCAG 2.0 to PDF without additional normative language?

The history of PDF demonstrates that electronic content accessibility, even in the light of WCAG 2.0, is not straightforward at all. WCAG 2.0 is written to be technically neutral for web content, so it should be no surprise that in some cases (PDF being one such), a technology-specific standard is vital to achieving consistent accessible outcomes.

The PDF Reference 1.0, the document detailing the technology of PDF, predated popular awareness of the web when Adobe Systems published it in 1993. While today's PDF 1.7 (now ISO 32000-1) details the mechanisms of PDF accessibility, the PDF Reference itself does not require accessibility features because PDF has many legitimate use-cases, printing systems, for example in which accessibility is irrelevant. The distinction is crucial.

The accessibility mechanism in PDF – the system of marked content and tags – is almost unrelated to the appearance of the PDF on screen and in-print. From an accessibility perspective there are advantages and disadvantages to this fact, but from a technical perspective, the extraordinary variety of ISO 32000-legitimate use-cases means developers need additional specific technical norms to achieve accessibility objectives in a consistent fashion.

What’s so great about consistency?

Consistency, a basis in “hardcopy” pages, flexibility and self-containment for portability and archiving are core features of PDF and irreducible qualities of the PDF experience.

The last twelve years have proven that accessibility models not structured around these core features are never going to result consistent universal access to PDF content based on a common understanding of what’s required when making and processing PDF files.

I've seen no evidence that implementing ISO 32000-1:2008 in light of WCAG 2.0 alone will result in consistent test or real-world experience for AT users.

Why PDF - and W3C - needs PDF/UA

In many cases, the PDF Reference (ISO 32000) provides inadequate technical detail to enable developers to generate consistent results when testing for WCAG 2.0 conformance. The observation that PDF developers needed specific normative language in order to reliably test and resolve accessibility technology in PDF was the rationale behind ISO 14289 in the first instance.

The most obvious of the problems is this: PDF developers may select from a variety of technical means when repurposing content. Some use PDF tags for logical ordering, and some do not, with a variety of methods in-between. This failure to agree on the priority and significance of logical vs. content order for accessibility purposes is the root cause of the general perception that PDF accessibility is arcane. The situation remains confused in leading applications to this day.

Screenshot of the top of W3C's WAI report on ISO 32000-1.A notably unfortunate example of this confusion is W3C’s own 2008 Accessibility Support Documentation for PDF, which attempts to map WCAG 2.0 Success Criterion 1.3.2 to ISO 32000-1:2008, Section Unfortunately, this section deals with “page content order”, not “logical order”, the proper subject of Success Criterion 1.3.2.

As the PDF Reference puts it in the first paragraph of this very section:

“The two orderings [logical and page content] are logically distinct and may or may not coincide.” (ISO 32000-1:2008 Section, paragraph 1)

If PDF is complex or ambiguous enough that even W3C's own report applies Success Criterion 1.3.2 (Level A) incorrectly, how "straightforward" can it be?

PDF/UA solves the problem with normative text stating that tag (logical) order is the organizing model for accessibility, thus setting the stage for consistent tools and end-user experience.

PDF/UA is also necessary simply because the PDF Reference provides no meaningful priority guidance on accessibility features. All aspects of tags in ISO 32000-1:2008 are “may” and “should” rather than “shall” statements. PDF/UA, by contrast, uses stronger “shall” and “should” statements in place of the weaker terms of ISO 32000-1. But that's a subject for another post!


During my testimony to the U.S. Access Board on March 1, I urged the US Access Board to include ISO 14289-1 (PDF/UA) as a referenced Standard in the refresh to Section 508 and wherever standards are set for accessibility in electronic documents.

PDF technology serves vital functions throughout the economy with specific features unlike those characteristically associated of web technologies. The Access Board is right to refer to industry standards in its rule making, but it should operate with caution when applying web content standards to all electronic content.

In the case of technologies such as PDF, the regulations should reference applicable ISO or other normative standards if available. For PDF, that means ISO 14289 (PDF/UA).

In the testimony I submitted to the Access Board I provide technical details and examples.

Return to Logical Structures | Read Duff Johnson's Disclaimer

Comments    [ Add a Comment ]

ANTONIO []    [ Dec 04, 2013 ]

WCAG priorities that might not coincide with what the public wants????

can someone answer this for me please

DUFFJOHNSON    [ Mar 13, 2012 ]


Excellent comments, thanks.

I’d just say a couple of things.

Yes, stretching WCAG 2.0 risks applicability. Since applicability is the entire point of standards in the first place, this issue deserves far more attention. Going from “web content” to “all electronic content” is just a colossal move.

It’s of course a very tempting move in the case of WCAG 2.0 because the standard proceeds from exceptionally general statements of principle (the four Principles) which are themselves more-or-less unarguable – at least, in principle.

I understand the purpose in writing towards technological neutrality when writing standards for a fast-changing world. I’m simply unconvinced that it’s possible to do so, and still retain the essential value of technical standards.

The elephant in the living room is the matter of validation and its close cousin: interoperability. Success Criteria 1.3.1 and 1.3.2 in particular has a very, very heavy burden to bear, especially in the world of PDF.

I agree, the larger problem is the meta-process.  There’s a place for normative text in a variety of spheres, but coordination is lacking.  I’m worried that the overall objective will suffer as a result.

JIM TOBIAS []    [ Mar 13, 2012 ]

I definitely agree with the underpinning of your argument about extending WCAG 2.0 to the non-web -- it stretches WCAG beyond where its contributors and editors expected, and thus risks inapplicability and at least unclarity. But I may disagree with where you take it.

To my mind, good implementation of any accessibility guidance will always take interpretation. Design decisions are so deeply contextual that absolute regulations will usually be out of place. This ain't electrical testing, where you can slap a meter on something and evaluate the single number you get back as 'pass' or 'fail'.

Furthermore, if we're being honest, we have to admit that there is no 'web' any more, in the sense of a unified set of technologies. It's a pragmatic, contingent world of slapdash development that are swapped out on a weekly basis by designers, or in-session by actions of the user.

So we're going to need ways to re-interpret any rules that are out there, in the light of the environment of use and technological evolution. I think it's better to have one integrated framework to do that with, rather than multiple ones that contend for jurisdiction. Nightmare scenario: WCAG 2.0 battles 'PDF-AG 1.0' and 'Document Content - AG 1.0' for dominance in the realm of federal documents.

In my comments on the 2nd ANPRM I recommended a 'Rolling Refresh' approach. When some narrow accessibility environment is threatening to evolve out of scope of the regs, the Access Board (or whoever -- this could easily be a WAI thing) empanels a rapid response team to either write new proposed regs, or, more frequently, issue guidance materials that interpret the existing regs.The Functional Performance Criteria would be especially useful for this.

I think this is a more realistic and feasible approach than trying to get the paper regs 100% right forever.