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Re: Media types

From: Dave Raggett <dsr@w3.org>
Date: Mon, 3 Nov 1997 10:58:39 -0500 ()
To: Jason White <jasonw@ariel.ucs.unimelb.EDU.AU>
cc: WAI HC Working Group <w3c-wai-hc@w3.org>
Message-ID: <Pine.WNT.3.95.971103103717.-163571L-100000@hazel.hpl.hp.com>
On Fri, 31 Oct 1997, Jason White wrote:

> I would like to summarise briefly in this forum the media type issue which
> I raised on the IG list yesterday.
> 
> The problem, essentially, is that if media type values are
> truncated prior to being matched against the media type of the
> output device, then so soon as parameterized values are
> introduced, the truncation which is mandated by the current HTML
> 4.0 draft will result in different media types being treated as
> identical. For example:  media="screen enlarged" and media="print
> enlarged"  become: media="screen" and media="print" respectively.

The motivation for the current rules is to avoid causing old
browsers problems when new media types are introduced or
elaborated with parameters. The idea is called "Future Proofing".
The truncation procedure is a fallback when the user agent doesn't
understand the parameters.

> Furthermore, since "screen"  is the default media type, a style
> sheet without an explicit media type value would be applied as
> part of the cascade, even if the default style sheet was of type
> media="screen enlarged" 

Is that a problem?  You would need to ensure the "screen enlarged" 
style sheet comes after such default screen style sheets, e.g. to
make sure the font-sizes and white space settings come out right.

By placing the "screen enlarged" style sheet before the "screen" 
default, new browsers that recognize the former would be happy while
older browsers would show the regular screen style sheet. The rules
in the latter would then override the rules in the former. Isn't
this the right thing to do?

Regards,

-- Dave Raggett <dsr@w3.org> http://www.w3.org/People/Raggett
phone: +44 122 578 2984 (or 2521) +44 385 320 444 (gsm mobile)
World Wide Web Consortium (on assignment from HP Labs)
Received on Monday, 3 November 1997 11:01:47 UTC

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