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exclusive media types and concurrent multimedia presentation

From: Al Gilman <asgilman@iamdigex.net>
Date: Fri, 30 Aug 2002 19:15:12 -0400 (EDT)
Message-Id: <>
To: www-style@w3.org

Where it says


    Media types are mutually exclusive in the sense that a user agent can
    only support one media type when rendering a document. However, user
    agents may have different modes which support different media types.


There is some risk that readers of this provision could think that a User
Agent, in the sense of the User Agent Accessibility Guidelines
<http://www.w3.org/TR/UAAG10/>, should not present the same content in
different media at once.

There are modes of access that people with disabilities depend on which rely
on such concurrent display of the same content in multiple media.

Based on the disposition of comments on the TV Profile, it is not our
understanding that CSS wishes to discourage displaying some content in
multiple ways at once, simply to point out that in this case each display is
styled in accordance with its own appropriate media type by its own
independent rendering process and cascade.

This is based on our understanding that the current CSS processing model
does not define a means to combine the cascades driving the styling of two

Possible re-write:


Media types are mutually exclusive in the sense that a given rendering
process will use a unique value from this type to represent the rendering
target in evaluating the cascade.  User agents may have different modes or
different concurrent channels which support different media types with
distinct rendering processes predicated on different values for the media


Please clarify the language in the document so as to eliminate the possible
interpretation that concurrent rendering to multiple media is disallowed
or discouraged.

Thank you,

/for PF Working Group <http://www.w3.org/WAI/PF/>
Received on Wednesday, 4 September 2002 08:33:55 UTC

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