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A.10.1

From: Charles McCathieNevile <charles@w3.org>
Date: Thu, 28 Jan 1999 01:18:54 -0500 (EST)
To: WAI GL <w3c-wai-gl@w3.org>
Message-ID: <Pine.LNX.4.04.9901280116420.26659-100000@tux.w3.org>
A.10.1 said:

 1. For auto-refreshing or timed response pages, provide a second copy of
the page where refresh only happens after a link has been selected (until
user agents provide this ability themselves). [Priority 1]

And I promised to write some techniques for it. Actually Daniel had asked
for a lot of detail. So here is my short essay...

Redirection of users can be very disorienting. It is quite common to find
a page which contains <META HTTP-EQUIV="REFRESH"
CONTENT="7;url=somewhere.com.nu"> and a note on the page explaining that
the page has moved, and asking the user to update their bookmarks.

This in fact violates the principle that standard mark-up should be used.
While META HTTP-EQUIV is standard HTML, REFRESH is not standard in HTTP -
it is simply recognised by many User Agents. There is a REDIRECT statement
which can be used analagously.

The actual accessibility problem is that reading speeds vary. What may
seem adequate time to let a user read the page could be completely
inadequate for somebody using a screen reader which doesn't get to the
line before the page has vanished, or somebody with a reading difficulty
who has been unable to get the message before something completely new has
appeared.

Similarly with timed-response requirements in active content. Although
there is often a strong motivation for the timing requirement, it can
cause problems for a number of groups and should be used with great care.

In pages which do this I have two suggestions: 
1. Don't. Leave the user to follow a link to the new page [CMN:: I don't
know how well this will sell]
2. Provide, first thing on the page, a link like "SLOW DOWN", to a version
of the page which doesn't change.


CMN:: This is really a problem that User Agents should solve. But they
generally don't, although Lynx does it beautifully. One of the interesting
things I have had happen with JAWS is that it is reading a page which is
two or three links behind where I am. That's confusing to me. Sigh.
Another of Daniel's judgement call problems.

--Charles McCathieNevile -  mailto:charles@w3.org
phone: * +1 (617) 258 0992 *  http://purl.oclc.org/net/charles
W3C Web Accessibility Initiative -  http://www.w3.org/WAI
545 Technology sq., Cambridge MA, USA
Received on Thursday, 28 January 1999 01:18:57 GMT

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