Learning Centers

PDF files can comply with Section 508. Now it's your move.

April 22, 2004


Editor's Note: This article is part of the Accessible PDF Learning Center

A blind person cannot read from a screen any more than from a printed page. Technologies nonetheless exist that allow blind and other disabled users impressively full-featured access to documents. To be accessible, however, the document contents must be available to these so-called "assistive" technologies.

To address the needs of visually impaired and other users who must employ assistive technology in order to read, the U.S. Congress passed Section 508 in 1998, an amendment to the Rehabilitation Act.

Section 508 requires U.S. Federal government agencies to procure accessible software and to produce accessible electronic documents. While the regulations went into effect in 2001, very, very few Federal government PDF files are known to comply - or have even been checked. The regulations can also apply in some instances to contractors who submit electronic documents to the federal government. The interested reader is strongly encouraged to consult the website set up to address this issue at www.section508.gov.

This article attempts an operational interpretation of Section 508 requirements for a common electronic document format: the humble PDF file.

Why PDF?

PDF files are uniquely valuable to government precisely because they guarantee authenticity to the printed original. It was for this reason that in 1997 the Federal government chose PDF for their electronic reading room standard.

From public-facing content (reports, papers, etc.), to record-keeping and high-use documents such as forms, PDF has remained the default choice for "final-form" official content.

It is this very quality, fidelity to a printed original, which makes accessibility hard to achieve in PDF. Until Acrobat 6.0, the issue remained almost unaddressed - the accessibility enhancement capabilities included with Acrobat were hopelessly flawed, and PDF was fast gaining a reputation as "inaccessible."

Since the release of Acrobat 6.0, however, PDF files are actually capable of far more structure than is required for compliance with Section 508. So much, in fact, that a very high degree of usability for the disabled has become a realistic goal. This new capability, powerful as it is, raises complex questions nonetheless, and significant pitfalls, pratfalls, pain-points and lawsuits lie in wait for the unwary.

What Compliance is Not

508 Compliance does not assure Usability (a.k.a. "happy users")

It is necessary to distinguish between Accessibility (what the law requires) and Usability (what works for the average user). The expectations of assistive technology users tend to explicitly revolve around usability, not accessibility. You might think these terms are, or at least should be, synonymous. A nice idea, but it?s not the case.

Section 508 delineates "formal" accessibility - requiring that complete document text and text equivalents of non-textual document content be deployable to the assistive technology devices available in the marketplace. Charitably, one could argue that the intent is to offload the usability issue to the interpretive software. One could also argue otherwise, but we?ll leave that one for the lawyers.

The point is this... a document might formally comply with Section 508, and still be incomprehensible when heard via a screen-reader. To assure that it is both compliant and comprehensible is a far more significant accomplishment - and arguably, is the only meaningful accomplishment.

Compliance CANNOT be achieved by software alone

To organize document content for assistive technology purposes, Adobe selected a method they call "tags." Users of Adobe System?s popular Acrobat program may have noted the availability of a free "Make Accessible" plug-in for Acrobat 5.0, which added tags to PDF content. A serious misnomer. Adobe renamed the menu item for this plug-in to "Add Tags to Document" in Acrobat 6.0 - a far more accurate, albeit less ambitious, description of its function.

The "Add Tags" feature in Acrobat 6.0, while a dramatic improvement over its hapless predecessor, will nonetheless demonstrate to all but the most casual user that simply "adding tags" does not ensure compliance with Section 508. If it did, you can rest assured that Adobe would trumpet the news far and wide. In fact, the term "Section 508" does not appear in the Acrobat Help file at all - need we say more?

Compliance is NOT a checkbox item

Attaining Section 508 compliance involves numerous policy questions ranging from the development of alternate text for images to the treatment of abbreviations. The process of ensuring compliance is rife with judgement calls, especially in balancing strict compliance against assured usability - a distinction with a significant cost differential.

Key Take-Aways
Accessibility starts with authors.
Section 508 compliance requires judgment and choices - it is not a checkbox.
The degree of difficulty in assuring compliance is a function of both content and layout complexity.
Disabled users don?t measure accessibility, they measure usability. Therefore, purely technical compliance with 508 is highly unlikely to resolve user complaints.
The Make Accessible plug-in (the "Accessibility - Add Tags to Document" menu item in Acrobat 6.0) does not make a PDF compliant with Section 508.
Neither the Accessibility Quick Check, nor the Accessibility Full Check in Acrobat 6.0 can verify compliance with Section 508.
First, the Good News

Many (possibly even most) PDF files are already largely compliant, and need little or no further work to become fully compliant. These files may be readily identified as follows:

  • The file consists of text (i.e., it is not just scanned images)
  • Layouts are extremely simple (i.e., there are only one or two columns of text)
  • There are no images, and tables are very simple and relatively small

Even if tags are not present in such a PDF, Adobe Reader 6.0 will make some fairly accurate assumptions regarding text flow, at least.

A Caution

Note that while such a document may readily comply, it may not be especially useable. After all, a 500-page document may be compliant without bookmarks, but if desired content is on page 450, then an assistive technology user may have to plow through each of the preceding 449 pages to get there! We recommend that ALL documents longer than a few pages include bookmarks that match the table of contents and major heading levels for this reason.

The Not-So-Good News: Alternate Text

Since Section 508 requires alternate text for each image, it is logical that achieving compliance should involve the author, the editor or at least the caretaker of the document text. Who else is supposed to come up with alternate text for each image? The graphic designer? What is the alternate text for, say, a pie-chart, anyhow? It?s an editorial, actually a policy-level, question. With respect, it is emphatically NOT a question for graphic-designers!

Even though it?s unavoidably their responsibility, document authors and editors are typically unfamiliar with the alternate text requirement. Even if they?ve heard of it, significant education is generally necessary to foster an understanding of alternate text, and especially, how to make it useable. This is not, by the way, an issue solely for PDF. Images in any electronic document format, HTML for example, need alternate text to comply with Section 508.

While PDF does support alternate text for discrete images, there is still no easy solution for adding alternate text to the image contents of PDF/Searchable Image files, a common "flavor" of PDF created from scanned documents. While I am aware of at least two work-arounds, neither are readily available via the Acrobat user-interface, and neither are completely satisfactory.

More Not-So-Good News: Tables

The Section 508 regulations include two separate provisions on tables - and for good reason. Conceived by and exclusively for sighted users, tables are one of the most difficult content delivery vehicles to make accessible. Imagine removing gridlines and cells to reduce a table to a stream of text, and you will understand why. The Section 508 regulation states that row and column headers be identified. While possible, compliance with this requirement will require mastery of the Tags palette in Acrobat 6.0. To ensure usability (as opposed to mere compliance), document authors may wish to consider using narratives to deliver information that might otherwise have implied the use of a table.

Still More Not So Good News: Text Flow

The simple way to understand text flow is to "Save As" your PDF to an RTF file using Acrobat 6.0. Open the resulting file in Word. You are now looking at the text flow a disabled user would have to contend with. If you can?t make heads or tails of the document in this fashion, then neither can they. The tags in the PDF need more work.

While the Section 508 regulations do not explicitly state that text flow must make sense to the user (that would imply that usability was the issue!), it is reasonable to assume that disjointed or erratic text flow violates the spirit of the regulation. Indeed, if the text flow is so bad as to make the document "unreadable," then the document simply does not comply. Sadly, on moderately complex documents, poor text-flow is generally the rule, not the exception.


Whether PDF, HTML, or some other format, sustained compliance with Section 508 requires a top-to-bottom review of the document authoring process. To best control compliance costs, document authors must be trained in authoring for document accessibility, especially with respect to the development of alternate text. Graphic designers must adopt policies that tend to reduce or eliminate the features that inhibit accessibility, such as the use of color to deliver information, or overly complex layouts.

If active compliance with Section 508 were to become routine rather than exceptional, it would demonstrate laudable progress towards a government for all. In addition to serving disabled users, there are other significant benefits from enhanced accessibility. Non-native language speakers, illiterate and learning-disabled users can all benefit from structured documents. Improved accessibility will enhance online interactions and reduce the time required to locate information. Document structure helps move content towards other devices (phones, PDAs, etc) - a significant capability as the information age matures.

While compliance with Section 508 has been mandatory for Federal agencies and their contractors since 2001, both the government that makes the rules and the electronic document industry that creates the tools have each only just begun to stir. PDF, for years, a vital component in the government document infrastructure, is now able to meet the challenge presented by Section 508. It is up to the authors, the designers and the policy makers to take the next step.

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