The PRE Element and Accessibility (3 of 3 LONG)

Sun Aug 31 14:51:07 EDT 2003

Even under the constrained conditions where replicating the exact white
space appearance of a document in order to meet legal requirements is at
issue, usage of <PRE> has recently been discouraged by an official of
the W3C's Web Accessibility Initiative on a W3C list. He proceeded to
provide more accessible, alternative markup suggestions (see
http://lists.w3.org/Archives/Public/w3c-wai-ig/2001AprJun/0106.html).

But, let us consider each guideline from WCAG 1.0 in turn:

          + "1. Provide equivalent alternatives to auditory and visual
            content."

Since <PRE> wraps text, this guideline does not apply.

          + "2. Don't rely on color alone."

<PRE> allows no color attribute tagging. Therefore, this guideline does
not apply.

          + "3. Use markup and style sheets and do so properly.

As noted above, <pre> has a specific intent. When used for a different
purpose than that for which it is intended, it arguably violates this
guideline in that it is not being properly used. As further noted above,
<pre> is easily used to counter the basic "themes" on which
accessibility in web content is based.

          + "4. Clarify natural language usage

This guideline refers to appropriate markup to indicate language and the
usage of abbreviations and acronyms. While document language can be
indicated within the <head> element, no mechanisms to tag abbreviations
and acronyms are allowed with text bounded by the <pre> element.

          + "5. Create tables that transform gracefully.

As noted above the WCAG specifically cites use of <pre> as inappropriate
markup for presenting tabular data.

          + "6. Ensure that pages featuring new technologies
transform gracefully.

<pre> wraps no new technologies.

          + "7. Ensure user control of time-sensitive content
changes.

<pre> does not support dynamically changing content.

          + "8. Ensure direct accessibility of embedded user
            interfaces.

<pre> wraps no user interface technologies.

          + "9. Design for device-independence.

Content wrapped with <pre> clearly violates this guideline in that it
cannot display as intended on various sized screens, particularly
screens on small devices such as wireless telephones and personal data
assistants.

          + "10. Use interim solutions.

This guideline does not apply to old technologies such as <pre> which
have always been supported by user agents. Rather, the problem with
<pre> is the other way around, it does not allow available more modern
technologies to make content wrapped in <pre> as accessible as it could
be.

          + "11. Use W3C technologies and guidelines.

While <pre> is a W3C specified technology, its use in the present
instance violates W3C guidelines as has been detailed in this document.

          + "12. Provide context and orientation information.

Since <pre> can only provide context and orientation information
visually, and then only when properly displayed, its use violates this
guideline.
          + "13. Provide clear navigation mechanisms.

<pre> affords no navigation mechanisms. Therefore, content wrapped with
<pre> will clearly violate this guideline.

          + "14. Ensure that documents are clear and simple.

In addition to reasons cited above, content wrapped in <pre> violates
this guideline simply because it does not allow the usage of additional
technological measures to clarify and elucidate content.
Undifferentiated blocks of text (which may well not wrap as intended, or
not at all thus forcing users to scroll left and right) is simply not a
presentational mechanism that assists comprehension. Users may
comprehend what is presented despite this tag element, in other words,
and not because of its use. Clearly, there are also numerous instances
where it can and will actively impede comprehension.
-- 

				Janina Sajka, Director
				Technology Research and Development
				Governmental Relations Group
				American Foundation for the Blind (AFB)

Email: janina at afb.net		Phone: (202) 408-8175