Accessibility Standards:
What’s the Difference Between WCAG, Sec. 508, and PDF/UA?

This short tutorial clears up the confusion about accessibility standards and helps you select the correct standard for your website, Word files, PDFs, and other digital content.

By Bevi Chagnon, PubCom
January 2017

A prospective client asked if we cover WCAG in our accessible Word and PDF classes.

Well, we do, but it’s only a short overview when we’re teaching Word and PDFs. Here’s why.

• WCAG (Web Content Accessibility Guidelines) is for websites and HTML-based material.
• The accessibility standard for documents, specifically PDF documents, is PDF/UA (PDF Universal Accessibility).

The two standards are designed to complement each other and harmonize, but there are significant differences and similarities that are detailed below.

So we thoroughly cover WCAG in our web accessibility classes, and focus on PDF/UA in our document accessibility classes.

How WCAG and PDF/UA are similar

• Both WCAG and PDF/UA have the same goal: to mark up content so that it is universally readable by computer technologies, including assistive technologies used by those with disabilities.
• Both standards use a similar — but not identical — set of universally recognized tags to mark up the content. Example: <H1> and <H2> designate heading levels 1 and 2 in both standards.
• Both standards are managed and published by the International Organization for Standardization (ISO) based in Europe, but each standard is developed by different nonprofit organizations.
• Many other technologies benefit from this common markup, such as CMS (content management systems), search engines, and cross-media publishing.

How the standards differ

Number of tags available:

• The HTML 5 mark-up language has nearly 200 tags. (See http://www.html-5-tutorial.com/all-html-tags.htm)  They are designed specifically for web content and how it is presented, interpreted, and rendered.
• The PDF standard has fewer than 30 PDF tags. (See https://helpx.adobe.com/acrobat/using/editing-document-structure-content-tags.html#standard_pdf_tags) They are designed specifically to label and interpret PDF document content.

The guidelines:

• The WCAG standard (that’s the standard, not the tags) has more than 50 checkpoints, success criteria, and guidelines that must be met. (See https://www.w3.org/TR/2006/WD-WCAG20-20060427/appendixB.html)
• The PDF/UA standard has 31 checkpoints. (See https://www.pdfa.org/wp-content/until2016_uploads/2014/06/MatterhornProtocol_1-02.pdf)

Who develops, approves, and publishes the standards:

•   +   
  WCAG is developed and written by the WAI (Web Accessibility Initiative), a subcommittee of the W3C (World Wide Web Consortium). WCAG 2.0 was approved and published by the ISO as ISO/IEC 40500:2012.
•   +   
  PDF/UA is developed and written by the PDFA (the PDF Association). PDF/UA-1 was approved and published by the ISO as ISO 14289-1.

A future blog will detail which tags are in which standard, but for now, here’s a short list of the tags most often confused.

1. <H1> – <H6> are for headings in both standards. No difference.
2. Bullet lists in HTML use <UL> and numbered lists use <OL>. But in PDFs, there’s only one tag — <L> — for both bulleted and numbered lists.
3. All lists in both standards use <LI> to label each individual item in the list. No difference.
4. But only PDFs divide <LI>s into sub-tags: <Lbl> for the bullet/number character and <LBody> for the text of the list item.
5. There is no summary tag available in PDFs, which is often used for tables in HTML.
6. There is no CSS (cascading stylesheet) formatting in PDFs. That’s only used with HTML and EPUBs.
7. All graphics use Alt-text in both standards. No difference.
8. However, only PDF has the Artifact tag which allows you to indicate that the graphic is insignificant and can be skipped by assistive technologies. HTML uses the null tag (empty quotes “”).

What this geek-speak means for you

Be careful. Just because a file uses pointy bracketed <tags> doesn’t mean that the tags are used for the same purpose, or that the same tags are used the same way by these different technologies. All markup languages use different sets of tags: XML, HTML, xHTML, PDF accessibility, IDTT, SGML, etc. Don’t make the mistake of confusing these very different markup languages and purposes, thinking that all pointy bracket <tags> are the same.

A <tag> is just a label encoded into the file. There are tag labels for HTML and others for PDF/UA. Some are the same, some aren’t.

And assistive technologies recognize only a small subset of any of these tag sets when reading, voicing, or presenting the content to those with disabilities.

This isn’t too confusing, is it? <grin>

That’s why we recommend taking specialized classes in how to make accessible content for your websites and for your Word, PowerPoint, and InDesign documents that will become PDFs.

Web accessibility isn’t the same as document accessibility. Similar, but not the same. (See our upcoming accessibility classes at http://www.pubcom.com/classes/calendar.php)

And I haven’t even mentioned EPUB accessibility, have I?! Wait, wait…that’s coming in another blog.

Is Sec. 508 the same as WCAG?

Sec. 508 is the US Federal regulation that mandates accessibility for all government ICT (information communications technology), which covers everything from websites and PDFs to emails, faxes, self-help kiosks at airports, cell phones, and many more technologies. The law is regulated by the US Access Board, a federal government agency, not an international nonprofit association like W3C and PDFA.

The law — Sec. 508 — covers much more than accessible websites and PDFs!

However, Sec. 508 doesn’t define any standards for accessibility — that’s done by the ISO and the international associations W3C and PDFA (see the previous sections of this blog).

Instead, Sec. 508 references the WCAG and PDF/UA international standards as the accessibility requirement for all US federal government ICT. This will take place in the forthcoming “Sec. 508 Refresh” in early 2017 when the US federal government formally adopts the International WCAG and PDF/UA standards.

[Author's note, January 6, 2017: The US Access Board (the federal government agency that regulates accessibility and Sec. 508) just announced it will be releasing the revised Sec. 508 requirements shortly. See https://twitter.com/AccessBoard/status/817120872473444354]

Many developed countries have already adopted the international standards, such as the United Kingdom, the EU, Australia, New Zealand, Canada, Israel, and others, as well as the United Nations. (See http://www.powermapper.com/blog/government-accessibility-standards)  In a way, the US will catch up to its worldwide colleagues in 2017.

At this time, Sec. 508 affects only federal government ICT, not state and local government ICT nor corporate ICT. However, many states have already adopted the federal Sec. 508 standards and eventually, all 50 states and territories will be under the regulation. In a few years, WCAG and PDF/UA will trickle down to the state and local governments, too.

Which standard to use

• If you’re working on websites, use the WCAG 2.0 standard (Web Content Accessibility Guidelines, https://www.w3.org/WAI/WCAG20/glance)
• If you’re creating documents and PDFs, use the PDF/UA-1 standards. (Universal Accessibility, http://www.pdfa.org/competence-centers/pdfua-competence-center)
• If you're not from the United States, you'll still use the above standards because they are the international ISO standards for accessible content that countries are adopting. Your country will have another law that requires the standards, not the US's Sec. 508. But the end result is the same.

Hope this helps you manage your organization's accessibility so that you meet the right standard for the right material.

— Bevi Chagnon
Founding Partner, PubCom

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Contents, this article

• How WCAG and PDF/UA are similar
• How the standards differ
• What this geek-speak means for you
• Is Sec. 508 the same as WCAG?
• Which standard to use
• Your Comments (on Facebook webpage)
• RETURN to the blog's homepage

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