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[CSS21] Media types

From: csant <csant@csant.info>
Date: Mon, 26 Jul 2004 14:55:08 +0200
To: www-style@w3.org
Message-ID: <opsbqwt6bjd84skq@claudido-xp.oslo.opera.com>

"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."
<URL: http://www.w3.org/TR/CSS21/media.html#media-types>

Multimodal browsers are about to become reality, and their case is not  
really covered by the spec.

The problem is that the spec clearly states "Media types are mutually  
exclusive", thus

(all | braille | embossed | handheld | print | projection | screen |  
speech | tty | tv)

However the statement "user agents may have different modes which support  
different media types" can be open to interpretation - no definition of  
'mode' is given.

In order to cover every possible scenario I'd suggest a re-definition of  
media types, grouping them in 'modes', subdivided in 'channels'.

There is three modes, 'visual', 'aural' and 'tactile'.

The visual mode can be sub-classified in dynamic (handheld,  
projection,screen, tty or tv) and static (print) channels.
There is only one dynamic channel for speech.
The tactile mode can be sub-classified in dynamic (braille) and static  
(embossed) channels.


visual   (handheld | projection | screen | tty | tv) & (print)
aural    (speech)
tactile  (braille) & (embossed)

visual and tactile can have an output on a different channel, which still  
belongs to the same mode: something can be seen on screen and  
simultaneously printed on paper, or touched on braille display and printed  
on paper by a
braille printer (embossed).

All media types belonging to one mode and one channel are mutually  


"He is old". But she is wrong. It is not age; it is that a drop has  
fallen; another drop.
~~~ Virginia Woolf
Received on Monday, 26 July 2004 08:55:52 UTC

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