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UAAG2: Rough Proposal on 2.3

From: Jan Richards <jan.richards@utoronto.ca>
Date: Thu, 13 Dec 2007 12:48:14 -0500
Message-ID: <4761705E.2070901@utoronto.ca>
To: WAI-UA list <w3c-wai-ua@w3.org>

2.3 Provide access to conditional content (P1)

Level A:

1. The user can browse and request the rendering of any items in a 
*conditional content stack* that are encoded in *technologies* that the 
user agent supports.

2. For visual user agents, if the user requests the rendering of an item 
in the *conditional content stack* that has on-screen dimensions that 
are larger than the default rendered item, then a configuration should 
control which dimensions are used.

3. If an item in the *conditional content stack* is plain text (e.g. alt 
text) then it is available programmatically even when not on-screen.

4. Previously rendered items can continue to be rendered alongside other 
items in the *conditional content stack* unless the user agent can 
detect a mutual exclusion.

Level AA:

5. The user can set preferences for which items in a *conditional 
content stack* are rendered by default.

6. The user is alerted to the presence of non-rendered items in the 
*conditional content stack* that are encoded in *technologies* that the 
user agent supports.

Level AAA:


"conditional content stack"
The set of *conditional content* items for a given position in content. 
The items may be mutually exclusive (e.g., regular contrast graphic vs. 
high contrast graphic) or non-exclusive (e.g., caption track that can 
play at the same time as a sound track).

"Conditional content"
Conditional content is content that should be made available to users 
only under certain conditions (e.g., based on user preferences or 
operating environment limitations). Some examples include:

- The alt attribute of the IMG element in HTML 4.
- OBJECT elements in HTML 4.
- The switch element and test attributes in SMIL 1.0.
- The NOSCRIPT and NOFRAMES elements in HTML 4.

Note: Specifications vary in how completely they define how and when to 
render conditional content.
Received on Thursday, 13 December 2007 17:48:15 UTC

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