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PDF Accessibility

508 Compliance Has Evolved

Equal access to the disabled is not only a national priority, but a global one as well. The forces driving this evolution are 1) the law in America and many other countries, 2) the tireless efforts of many individuals and organizations, 3) money – 20% of consumers have some kind of handicap, and 4) it’s simply the right thing to do. The result is that accessibility has improved dramatically.


“508 compliant PDF” is now understood to mean “Accessible PDF”.


The Access Board’s 508 Compliance Standards are meant to ensure equal access. Their focus was more on “access” and less on “equal” meaning the handicapped could get the information but it wasn’t always easy. As noted in Standards and Requirements (What We Do page), individual agencies have tried to address this by adding their own requirements and the international community, represented by W3C, has done the same in their guidelines (WCAG). Naturally, multiple standards/guidelines leads to confusion, not clarity.

With the broadened interpretation of the 508 law and ADA compliance, public content residing on private industry sites must also conform. This expansion into the private sector has furthered the need for uniformity of “equal access”.

Current status of Accessible PDF:

Perhaps the most telling sign of accessibility’s status comes from NetCentric, the maker of CommonLook (CL). CL continues to lead the industry as the most efficient software to remediate PDFs. It’s most recent update offers the following accessibility checks; 508 Compliance, HHS, WCAG, and PDF/UA. Four standards!

PDF/UA is dawning:

In fact, it’s here but the world is slow to turn.

Adoption of universal accessibility verbiage & guidelines: Appropriately, “508 Compliant” is now referred to as “Accessible”.  Additionally, the undeniable value and universal acceptance of PDF as the format of choice is demonstrated by the fact that accessible PDF requirements are specified as Techniques for WCAG 2.0.

New 508 Standards

As of 2017, all 508 standards for PDFs must point to WCAG 2.0 AA techniques.

PDF/UA (PDF/Universal Accessibility) = PDF ISO 14289: PDF is the format. UA designates that the PDF is tagged in such a way as to allow conformance with WCAG 2.0 (as they relate to documents). According to the standard, “The primary purpose of ISO 14289 (known as PDF/UA) is to define how to represent electronic documents in the PDF format in a manner that allows the file to be accessible.”

The Matterhorn Protocol = PDA’s (PDF Association) recommended criteria for PDF accessibility: It consists of 31 Checkpoints comprised of 136 Failure Conditions.

WCAG 2.0 = W3C’s accessibility guidelines: These international guidelines have been adopted by both the public & private sectors. In January 2017, The Access Board adopted the revised Section 508 standards. The PDF standards now point to specific WCAG techniques. The confusion about agency/specific standards should no longer be an issue. To quote Bruce Bailey, Access Board PDF expert, “Agencies can have requirements that go beyond the minimum baseline established by 508 (i.e., WCAG 2.0 Level AA).  Those additional requirements should be considered with some caution, as there is probably good reason why those additional requirements are not already success criteria in WCAG 2.0.”

PDF Accessibility

Confirmed by testing with PAC along with human validation.

PDF-Accessibility-Checker (PAC 2) tests for WCAG or PDF UA: Both W3C and PDF/A recommend PAC for checking PDF accessibility. It is free software.

Important note: Software checks for approximately 2/3 of the guidelines. The rest requires human checking. A knowledgeable remediator can examine a PDF and determine if it will be interpreted properly by assistive technologies, almost. There are certain characters and character combinations that can be misinterpreted. The answer is to have the file listened to by an AT user.


“508 compliant PDF” is now understood to mean “Accessible PDF”. WCAG 2.0 AA PDF techniques are now the guidelines and are compatible with PDF/UA’s Matterhorn Protocol criteria.

Keeping it simple: For PDFs, 508/ADA/WCAG are synonymous.

Caution: PDF Accessibility will always be a work-in-progress.

Consistency is everyone’s friend so it’s nice to know that uniform accessibility terminology and standards are stabilizing. But;

Governmental impediments: It’s also wise to understand that agencies (let alone governments) are huge bureaucracies. By definition, they’re slow to change. It takes a lot of good intention to overcome turf protection, legal morass, budget considerations, and everything else associated with politics and market pressures.

“Accessible PDF” has Universal Acceptance?

Not yet, but progress is being made.

Volume impediments: There are multiple hundreds of thousands of PDFs posted on any one agency’s site. Couple that with the number of PDF Accessibility criteria (regardless of which standard) and you’ll realize that it takes an army to check for 508 compliance. Adopting new and expanded accessibility standards for this volume of work has considerable ramifications.

Subjectivity impediments: Over a third of the criteria must be checked by humans. Many of these criteria are subjective.
Words like “acceptable” & “adequate”.
These words are necessary to convey the intent of some accessibility requirements, but they also open the door for interpretation.

Example of adequate alt text:
• One blind AT user may find it helpful to hear verbose explanations while another may perceive them to be overkill or even insulting (I’m blind, not stupid). And auditors (accessibility testers) are human which leaves them susceptible to frailties. What is “adequate” to a tester in the morning may not be “adequate” in the afternoon.

“Proper” tagging is debatable.
Examples of just link-related things that misinformed testers can “fail” a file for:
• Links must have alt text. The reason for this requirement is to help the blind search on links (“pull up” and tab through all the links). Without a brief description of the URL, the user can’t discern what the link is for. However, links are used in a Table of Contents (TOC). It makes no sense to give a TOC item alt text because the item is self-explanatory. Alt text for URLs are important. Alt text for TOC links are redundant. This is confusing/annoying to the AT user but some testers believe “going by the book” trumps ease of accessibility.
• Nest the link words & OBJR in <Link> and the <Link> in a <Reference>. Proper tag structure for TOC items has been a contentious issue for years. Currently the HHS site refers to the VA site for details. The VA uses the additional <Reference> tag which causes AT to repeat content, twice! Again, some testers believe “going by the book” trumps ease of accessibility.
• Order of URL (text) and OBJR (annotation) under <Link>. The VA example shows the URL first and the OBJR second. There are a few legitimate ways to tag links. Depending on which method you use, the order of URL and OBJR is reversed. Their order has NO bearing on accessibility yet some testers insist on URL first.

The problem of testers using poor judgement is as costly as it is real.