LIS 523/5 - Accessibility

Why Accessibility is Important

W3C Guidelines

The World Wide Web Consortium proposes the following guidelines for accessibility.
  1. Content that allows presentation according to the user's needs and preferences.
    1. Text equivalents for all non-text content.
    2. Text equivalents synchronized with multimedia presentations.
    3. Synchronized description of essential visual information in multimedia presentations.
    4. Markup or a data model used to provide logical structure of content.
    5. Content and structure separate from presentation (e.g., by using style sheets).
    6. Device-independence (e.g., either mouse or keyboard may be used).
    7. Content that remains accessible when newer technologies are not supported or turned off.
  2. Content that allows interaction according to the user's needs and preferences.
    1. Consistent interaction behaviors and navigation mechanisms.
    2. Content that does not interfere with the user's ability to concentrate.
    3. User control of mechanisms that cause extreme changes in context (e.g., opening a new browser window).
    4. User control over how long they can spend reading or interacting.
    5. Where searching is allowed, a variety of search options.
  3. Ease of comprehension.
    1. Consistent presentation.
    2. Emphasis on structure.
    3. Clear and simple writing.
    4. Use of multimedia for illustration.
    5. Summarizing of complex information.
    6. Definition of key terms, etc.
    7. Division into smaller, more manageable units.
    8. Compatibility and interoperability.
      1. Languages, API's, and protocols that support these guidelines,
      2. used according to specification.
      3. Assistive-technology compatible user interfaces.

An Example

One common cause of accessibility problems is the use of frames. For example, when the former FIMS home page was accessed with a simple browser using text-only mode, the user would get the following:
This site uses frames and is designed for

v.4 + browsers
16 bit high colour or better
graphic setting of 800x600

Faculty of Information and Media Studies
University of Western Ontario
To find any links, the user had to dig into the HTML source code to find out the initial frame contents.

The revised home page (, which does not use frames, is more helpful. Here is what it looks like in one version of the Lynx browser:

Faculty of Information & Media Studies - The University of Western O (p1 of 2)

   FIMS - Faculty of Information and Media Studies
   Graphic Montage of Images to Represent the Faculty of Information and
   Media Studies

The menu on some pages in this site will not work with JavaScript disabled.
  You can navigate between pages using the SiteMap (there is a link at the
                           bottom of every page).

   About the Faculty
   BA in Media, Information & Technoculture
   Degree/Diploma in Media Theory & Production
   MA in Journalism
   MA in Media Studies
   PhD in Media Studies
   Master of Library and Information Science
   PhD in Library and Information Science
   [new.gif] MA in Popular Music and Culture
   People and Groups

-- press space for next page --
  Arrow keys: Up and Down to move. Right to follow a link; Left to go back.
 H)elp O)ptions P)rint G)o M)ain screen Q)uit /=search [delete]=history list


Tools to assess page accessibility are available on the Web, and also as features in some Web page creation software. For example, Dreamweaver has a "Check Page for Accessibility" extension that alerts developers to accessibility problems and their location in source code. Typically, however, such tools alert page creators, not only to real accessibility issues with their pages, but also to many so-called problems that are of no particular importance (such as not having a doctype statement before the HTML code, or even not having a longdesc attribute for an image in addition to an alt attribute).

Users with disabilities may use special Web services to convert files to more usable formats on the fly. If parts of your site are password-protected, use of such services could pose a security threat, since users may be forced to transmit their passwords as plain text to the accessibility services. You may therefore be better advised to provide for accessibility on your site itself.

Special rendering options for speech generation and braille can be specified in a style sheet in @media aural{ } and @media braille{ } blocks. The style sheet specification also provides for a number of characteristics and settings for speech generation from HTML elements.

For More Information


Last updated April 23, 2007.
This page maintained by Prof. Tim Craven
E-mail (text/plain only):
Faculty of Information and Media Studies
University of Western Ontario,
London, Ontario
Canada, N6A 5B7