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Re: technique addition for marking/tagging the DOM

From: Richard Schwerdtfeger/Austin/IBM <schwer@us.ibm.com>
Date: Thu, 19 Oct 2000 16:52:31 -0500
To: Ian Jacobs <ij@w3.org>
Cc: User Agent Guidelines Emailing List <w3c-wai-ua@w3.org>
Message-ID: <OFC50428EA.25A43627-ON8625697D.0075BE98@raleigh.ibm.com>
Ian,

Here are some techniques to meet my action item regarding manipulation of
the DOM. I am not sure where they should be placed.

Supporting DOM write capabiility:

It is very helpful for assisistive technologies to have the ability to
modify the Document Object Model.

Allowing an AT to have write access would allow the asssitive technology to
modify the attribute list of a document. Through the use of the DOM
attribute list it is possible to add information into the DOM that will not
be rendered by the user agent. It is also possible to add entire nodes to
the DOM with AT specific tags that are not renderable by a user agent since
it is unaware of their function.

This can have peformance benefits for an assistive technology. For example,
if an asssistive technology had already traversed a portion of the DOM and
it new that the section was not renderable, the assistive technology could
mark the section to be skipped. An example of this might be the existence
of a style element.

Another benefit is to add information that is needs to be rendered in audio
but would not be stored directly in the DOM during normal parsing
operations. An example of this is an ordered list. The IE 5.5 HTML DOM
tells you that list elements are part of an ordered list but it does not
tell you each list element's number. By detecting the existence of an
ordered list an assistive technology could add the actual list element
number to each list entry in its attribute list. When it came time to
render the list the number could be retrieved and spoken by the rendering
component such as an audio browser front end. Furthermore, the AT component
which added the numeric information could mark that section as having been
traversed and updated to prevent having to recompute and store the numeric
information on the next pass through by the user.



Rich Schwerdtfeger
Senior Technical Staff Member
IBM Accessibility Center
Research Division
EMail/web: schwer@us.ibm.com

"Two roads diverged in a wood, and I -
I took the one less traveled by, and that has made all the difference.",
Frost
Received on Thursday, 19 October 2000 17:52:38 GMT

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