Everyone, Everything, Connected was the slogan of the 6th WWW Conference
held earlier this year in California, but how accessible is the web? In
theory, since most documents on the web will be in HTML, a structured markup
language, the web should be an ideal, widely accessible, information delivery
medium. In practice, however, the increasingly visual nature of the web
is in danger of alienating a large group of users, including the visually
disabled, and as someone recently described themselves, the 'GUI blind'.
These users include all those with slow Internet connections, perhaps accessing
the Internet over a slow modem from home, or in one of the many third world
countries with inadequate national communications networks.
The main cause of inaccessibility is poor design, but with a little thought
visually pleasing pages can be designed that can also be viewed by text
based browsers and understood by screen readers. Obviously not all web pages
will be accessible to everyone, some by the very nature of the information
they are conveying will have limited accessibility. However, it is important
that accessibility should always be a concern when creating new pages.
Listed below are a few simple pointers to improving the accessibility
of your web pages.
Make your documents consistent - if navigation aids are always in the
same place on every page your site will be much easier to get around.
Use only standard HTML tags - HTML is a structured markup language, the
tags are formatting constructs. Braille translation software relies on proper
use of these tags to construct a meaningful translation. Some non-standard
tags, such as BLINK and MARQUEE cannot be read by screen readers.
Use the ALT tag with images. If the image is purely decorative using
Alt=" " or Alt="Null". For other images provide short,
useful descriptions, for example for list bullets use Alt="*".
If the image is complex, include a description nearby rather than a long
ALT tag.
Where possible include text alternatives to image maps.
As it is often difficult for blind users to identify hyperlinks, many
screen readers will provide a list of the links extracted from the surround
text. Therefore, make your anchors meaningful - try just reading out the
anchors to see how useful they are. For example:
<a href="mailto:sue.cunningham@mcc.ac.uk">E-mail
Sue.Cunningham@mcc.ac.uk</a> with comments
Is more helpful than:
Click <a href="mailto:sue.cunningham@mcc.ac.uk">here</a>
to send us your comments.
Always provide an alternative mechanism for on-line forms, for example
providing an e-mail or other contact address.
Use punctuation. Screen readers use punctuation to determine when to
pause when reading the screen, so include all standard punctuation, for
example, full stops at the end of list items.
Tables pose a special problem for screen readers as they read across
the screen a line at a time, regardless of columns. This can render a multi-column
document almost impossible to decipher. Consider providing a plain text
alternative.
Avoid frames where possible, and always provide an alternative. Frames
can greatly increase the difficulty in navigating through a site for many
users, and screen readers working with frame capable browsers will not be
able to deal with frames successfully.
Provide text transcriptions or descriptions for all audio clips.
File formats other than HTML (e.g. Adobe Acrobat) should be used only
as alternatives to, rather than replacements for, HTML files.
Always test your pages using multiple viewers. If you don't have access
to a range of browsers, try using Bobby. Bobby is an on-line validation
service that will check your pages for compatibility with a range of browsers,
and highlight any potential accessibility problems, e.g. missing ALT tags.
Bobby can be found at http://www.cast.org/bobby/
The World Wide Web Consortium (W3C) is committed to accessibility, stating
that 'All the protocols and languages we issue as Recommendations should
meet or exceed established accessibility goals. In addition, we will actively
encourage the development of web software and content that is accessible
to people with most disabilities'. It recently launched the International
Web Accessibility Initiative 'to promote and achieve web functionality for
people with disabilities'.
The drafts being considered for Cougar (code name for the next version
of HTML) include several accessibility features, such as an extension for
tables which would support rendering to Braille or speech, additional markup
for forms which would aid screen readers, and better handling of client-side
image maps for non-graphical browsers.
Despite improvements in technology and standards, the biggest single
thing that will improve web accessibility will always continue to be thoughtful
page design using valid HTML.
Links to pages on accessible web design http://www.nyise.org/speech/access.htm
W3C disabilities developments page http://www.w3.org/pub/WWW/Disabilities/
Making the web Accessible for the Blind and Visually Impaired - Mike
Paciello http://www.yuri.org/webable/mp-blnax.html
WWW: Design for Accessibility. Ability (The Journal of the BCS Disability
Group) Issue 18
Bobby (web validation service) http://www.cast.org/bobby/
Sue Cunningham
The Future
References
SIMA Multimedia Support Officer
Computer Graphics Unit
Manchester Computing
University of Manchester
Manchester M13 9PL
UK
Tel: +44 161 275 6095
Fax: : +44 161 275 6040
sue.cunningham@mcc.ac.uk
http://info.mcc.ac.uk/CGU/mmsup.html