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Re: Extensions to CSS3 selectors

From: Ian Graham <igraham@smaug.java.utoronto.ca>
Date: Sun, 23 Apr 2000 13:34:02 -0400
To: Tim Bannister <isoma@compsoc.man.ac.uk>
cc: JOrendorff@ixl.com, www-style@w3.org
Message-ID: <Pine.SGI.4.05.10004231308350.28892-100000@smaug.java.utoronto.ca>
On Sat, 22 Apr 2000, Tim Bannister wrote:

> On Fri, 21 Apr 2000, Jonas Sicking wrote:
> 
> >I have some suggestions for extensions to the current CSS3 selector WD:
> >
> >1. Empty cells
> >Some way of selecting empty elements, my suggestion is a pseudo-class called
> >':empty'. This could be used to supply defaultvalues through CSS and also
> >functions like marking of missing data and more powerful hanling of empty
> >cell then the current 'empty-cells' property.
> 
> Would you consider an element such as <HR /> as empty?  What about
> <TEXTAREA></TEXTAREA>?
> 
> Either way, I suggest that it's a good idea to define precisely what
> constitutes an empty element, especially if the element is replaced.

I would suggest (see [1]) the following specification:

:empty  The Empty-Element Pseudo-Class.

  The empty-element pseudo classes matches elements that are empty
  of significant content. In this context, "empty of significant 
  content" has the following meanings depending on how the markup
  is being processed: 

  1) If the data are being processed by an HTML processor, then an
     element is empty of significant content if:
     (a) The element is an HTML element declared to be empty, or
     (b) The element consists of a start and stop tag, but the
         content of the element consists only of zero or more
         white space characters. White space 
         characters are defined as in production 3 of the 
         XML 1.0 specification, namely:
         (#x20 | #x9 | #xD | #xA)+      

  2) If the data are being processed by an XML processor, then
     an element is empty of significant content if:
     (a) The element is written as an empty-element tag, or
     (b) The element consists of a start and stop tag, but the
         content of the element consist only of zero or more 
         XML white space characters.

I should note that Jason Orendorff [1] was the first to sugest
this pseudo-class, but the note appeared on the www-html list before
the topic got cross-posted to www-style

[1] http://lists.w3.org/Archives/Public/www-html/2000Apr/0068.html 

Ian
--
Ian Graham ......................... Centre for Academic Technology
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University of Toronto                             Fax: 416-978-7705
..................... http://www.utoronto.ca/ian/ .................
Received on Sunday, 23 April 2000 13:35:30 GMT

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