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Action-352 Write IER for 3.1.4 (modify 3.1.2)

From: Jim Allan <jimallan@tsbvi.edu>
Date: Thu, 22 Apr 2010 11:45:58 -0500
To: "'WAI-UA list'" <w3c-wai-ua@w3.org>
Message-ID: <005a01cae23b$48b304c0$da190e40$@edu>
3.1.4 Rendering Alternative (Enhanced): Provide the user with the global
option to configure a cascade of types of alternatives to render by default,
in case a preferred type is unavailable. If the alternative content has a
different height or width, then the user agent will reflow the viewport.
(Level AA)

#  Intent of Success Criterion 3.1.4:
This is an enhancement of 3.1.2 Configure Default Rendering. The author may
provide several pieces of alternative content. For example, an image of the
Mona Liza may have some combination of the following alternative content: a
low resolution image, a high resolution image, a title using the title
attribute, a short description using the alt attribute, a detailed longer
description using the longdesc attribute. This SC allows the user to
globally set not only a default rendering for the image, but to also specify
if choice 1 is not provided by the author the choice 2 is rendered and so
forth down the list of user selected options for rendering. This is a global
option because it would be an unreasonable burden for the user to have to
change the rendering options every time they visit a new page.

# Examples of Success Criterion 3.1.4:

    * In the browser's preferences dialog box, a user specifies that they
want alternatives rendered in the following order of preference, if the
selected alternative is not available choose the next item on the list until
all options have been exhausted
1. Alt text displayed in place of images
2. title text displayed in place of images
3. longdesc link is displayed in place of image
4. high resolution image
and that the document should reflow to allow the displayed alternative to be
displayed rather than truncated. Note: Item 1 would be the default and
satisfy 3.1.2
    * In the browser's preferences dialog box, a user assigns a number to
the available alternatives supported by the user agent, and thus establishes
the cascade of alternative ("fallback") content to display the for embedded
objects, such as videos. The first item in the cascade would be the default.
    

Jim Allan, Accessibility Coordinator & Webmaster
Texas School for the Blind and Visually Impaired
1100 W. 45th St., Austin, Texas 78756
voice 512.206.9315    fax: 512.206.9264  http://www.tsbvi.edu/
"We shape our tools and thereafter our tools shape us." McLuhan, 1964
Received on Thursday, 22 April 2010 16:57:48 GMT

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