Non-W3C Technologies Techniques for Web Content Accessibility Guidelines 1.0

W3C Working Draft 23 June 2000

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Wendy Chisholm, W3C,
Gregg Vanderheiden, Trace R & D Center, University of Wisconsin -- Madison
Ian Jacobs, W3C


This document describes techniques for satisfying the checkpoints of "Web Content Accessibility Guidelines 1.0" [WCAG10] when authoring with non-W3C technologies such as Flash and PDF.

This document is part of a series of accessibility documents published by the Web Accessibility Initiative. "Techniques for Web Content Accessibility Guidelines 1.0" [WCAG10-TECHS] contains additional techniques and references for other formats and languages.

Status of this document

While Web Content Accessibility Guidelines 1.0 strives to be a stable document (as a W3C Recommendation), the current document is expected to evolve as technologies change and content developers discover more effective techniques for designing accessible Web sites and pages.

This is a W3C Working Draft for review by W3C Members and other interested parties. It is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to use W3C Working Drafts as reference material or to cite them as other than "work in progress". This is work in progress and does not imply endorsement by, or the consensus of, either W3C or participants in the Web Content Accessibility Guidelines (WCAG) Working Group.

This document has been produced as part of the W3C Web Accessibility Initiative. The goal of the Web Content Guidelines Working Group is discussed in the Working Group charter.

A list of current W3C Recommendations and other technical documents can be found at http://www.w3.org/TR.

Please send detailed comments on this document to w3c-wai-gl@w3.org.

Table of Contents

1 Macromedia Flash

1.1 Static images

Checkpoint in this section: 1.1.

The Macromedia Flash Generator may create simple (non-interactive) animations or a static images to be included in an HTML document with the IMG element. An "alt" attribute is required per Checkpoint 1.1.

To use Generator to dynamically output a .gif stream instead of a Flash stream, add the "type=" attribute with an appropriate value.


<http://path/flashtemplate.swt?type=gif&param1=val1&param2=val2> "
height="111" border="0" width="222" naturalsizeflag="1"
align="BOTTOM" alt="Description of the Image">

Critical Elements: The "type=gif" parameter/value.

1.2 Providing alternative images

Checkpoint in this section:

It is possible to determine (via Javascript) if the user has installed the Flash plug-in, and provide an alternative image if they have not. The following code is derived from code that was automatically generated by Flash 4. It is modified to merely trigger on the presence of the Flash plug-in.


<!-- Image Map -->
var UseFlash = 0;
if (navigator.mimeTypes && navigator.mimeTypes["application/x-shockwave-flash"] ) {
  // Check for Flash version 3 or greater in Netscape
  var plugin = navigator.mimeTypes["application/x-shockwave-flash"].enabledPlugin;
  if (plugin && parseInt(plugin.description.substring(plugin.description.indexOf(".")-1))>=3
    UseFlash = 1;
} else if (navigator.appName && navigator.appName.indexOf("Microsoft") != -1 && navigator.userAgent.indexOf("Windows") != -1 && navigator.userAgent.indexOf("Windows 3.1") == -1) {
   // Assume any Windows IE except for Windows 3.1 supports the
   // OBJECT tag UseFlash = 1;
if ( UseFlash ) {
   // Use Flash player
   // Although these alt tags do not apparently seem to be supported with the plug-in,
   // they are included on the chance they are supported in an upgrade
   document.write('<object width="400" height="400" alt="Object Map 
   of Alaska" classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" '); 
   document.write(' '); 
   document.write(' WIDTHU0 HEIGHT35 
   codebase="http://active.macromedia.com/flash2/cabs/swflash.cab#version=4,0,0 ,0" 
   // the next 'document.write' line will need to be modified to point to your
   // file and to use your params
   document.write('<param name="movie" value="http://path/flashtemplate.swt?param1=val1¶m2=
   val2 <http://path/flashtemplate.swt?param1=val1¶m2=val2> "><PARAM 
   NAME=quality VALUE=high> <param name="bgcolor" value="#FFFFFF"> ');
   // the next 'document.write' line will need to be modified to point to your 
   // file and to use your params
   document.write('<EMBED ALT="Embed Map of Alaska"
   <http://path/flashtemplate.swt?param1=val1¶m2=val2> " quality=high
   bgcolor=#FFFFFF ');
   document.write(' swLiveConnectúLSE WIDTHU0 HEIGHT35');
   document.write(' TYPE="application/x-shockwave-flash"
} else if (!(navigator.appName && navigator.appName.indexOf("Netscape")>=0
&& navigator.appVersion.indexOf("2.")>=0)) {
   // Netscape 2 will display the IMG tag below so don't write an extra one
   // You will need to modify the SRC param
   document.write('<img src="http://path/flashtemplate.swt?type=gif¶m1=val1¶m2=
   val2<http://path/flashtemplate.swt?type=gif¶m1=val1¶m2=val2> " alt="GIF 
   Object Map of Alaska" WIDTHU0 HEIGHT35 border="0">
// You will need to modify the SRC param as follows
<http://path/flashtemplate.swt?type=gif¶m1=val1¶m2=val2> "
ALT="NOEMBED GIF Object Map of Alaska" WIDTHU0 HEIGHT35 usemap="#AK"
// You will need to modify the SRC param as follows
<http://path/flashtemplate.swt?type=gif¶m1=val1¶m2=val2> "
ALT="NOSCRIPT GIF Object Map of Alaska" WIDTHU0 HEIGHT35 usemap="#AK"

2 Adobe PDF

In the works...please stay tuned.


Web Content Guidelines Working Group Co-Chairs:
Jason White, University of Melbourne
Gregg Vanderheiden, Trace Research and Development
W3C Team contact:
Wendy Chisholm
We wish to thank the following people who have contributed their time and valuable comments to shaping these guidelines:
Harvey Bingham, Kevin Carey, Chetz Colwell, Neal Ewers, Geoff Freed, Al Gilman, Larry Goldberg, Jon Gunderson, Eric Hansen, Phill Jenkins, Leonard Kasday, George Kerscher, Marja-Riitta Koivunen, Josh Krieger, Chuck Letourneau, Scott Luebking, William Loughborough, Murray Maloney, Charles McCathieNevile, MegaZone (Livingston Enterprises), Masafumi Nakane, Mark Novak, Charles Oppermann, Mike Paciello, David Pawson, Michael Pieper, Greg Rosmaita, Liam Quinn, Dave Raggett, T.V. Raman, Robert Savellis, Jutta Treviranus, Steve Tyler, and Jaap van Lelieveld

The original draft of this document is based on "The Unified Web Site Accessibility Guidelines" [UWSAG] compiled by the Trace R & D Center at the University of Wisconsin. That document includes a list of additional contributors.

3 References

For the latest version of any W3C specification please consult the list of W3C Technical Reports at http://www.w3.org/TR.

"Web Content Accessibility Guidelines 1.0", W. Chisholm, G. Vanderheiden, and I. Jacobs, eds., 5 May 1999. This WCAG 1.0 Recommendation is http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505.
"Techniques for Web Content Accessibility Guidelines 1.0", W. Chisholm, G. Vanderheiden, I. Jacobs, eds. This document explains how to implement the checkpoints defined in "Web Content Accessibility Guidelines 1.0". The latest draft of the techniques is available at http://www.w3.org/WAI/GL/WCAG10-TECHS/.

4 Resources

Note: W3C does not guarantee the stability of any of the following references outside of its control. These references are included for convenience. References to products are not endorsements of those products.

4.1 Accessibility resources

"The Unified Web Site Accessibility Guidelines", G. Vanderheiden, W. Chisholm, eds. The Unified Web Site Guidelines were compiled by the Trace R & D Center at the University of Wisconsin under funding from the National Institute on Disability and Rehabilitation Research (NIDRR),  U.S. Dept. of Education.

Level Triple-A conformance icon, W3C-WAI Web Content Accessibility Guidelines 1.0