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Re: [CSS21][css-device-adapt] Multiple groups in the "Media" line of properties/descriptors

From: Rune Lillesveen <rune@opera.com>
Date: Thu, 28 Feb 2013 15:34:26 +0100
To: "www-style@w3.org" <www-style@w3.org>, "Simon Sapin" <simon.sapin@kozea.fr>
Message-ID: <op.ws7z3oq78isf1p@id-c1005.oslo.osa>
On Thu, 28 Feb 2013 13:06:16 +0100, Simon Sapin <simon.sapin@kozea.fr>  

> Properties and descriptors have a "Media" line described in of  
> CSS 2.1:
>> This part indicates the media groups to which the property applies.
>> Information about media groups is non-normative.
> When this line lists multiple groups, it is unclear whether the property  
> should apply when the current media is in *any* on the listed group or  
> *all* of them.
> This happens at least for the 'cursor' property (visual, interactive)  
> and for the @viewport descriptors defined in css-device-adapt (visual,  
> continuous).
> In both cases "all" makes more sense than "any".
> Should we errata CSS 2.1 ?

It's not quite "all" nor "any", I think. Look at the media groups table in  
CSS21 [1]. When a property applies to all groups in a table column, none  
is listed in "Media:". If it doesn't apply to some of the groups in a  
column, those it applies to are listed.

For cursor, neither "continuous" nor "paged" is mentioned because it  
applies to both. "visual" is listed because it doesn't apply to any of the  
others in that column. It applies to both "bitmap" and "grid", so none  
mentioned. It doesn't apply to "static" content, so list "interactive".

The intended meaning in css-device-adapt is that the descriptors don't  
apply to "paged" media, so "continuous" is listed. Likewise for "visual".

Anyway, it should probably be clarified.

> By the way, css-device-adapt kind of implies in its Introduction that  
> the whole spec only applies in continuous media. It would be nice to  
> make this more explicit.

The Introduction refers to the viewport as defined in CSS2.1 [2]. That  
definition talks about continuous media. I think that's the story behind  
why I didn't write it more explicitly.

I'll add text to a normative section to make it more explicit.

[1] http://www.w3.org/TR/CSS21/media.html#media-groups
[2] http://www.w3.org/TR/CSS21/visuren.html#viewport

Rune Lillesveen
Received on Thursday, 28 February 2013 14:34:57 UTC

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