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RE: [CSS21] 9.2 Anonymous boxes

From: Arron Eicholz <Arron.Eicholz@microsoft.com>
Date: Wed, 16 Mar 2011 20:00:44 +0000
To: Anton Prowse <prowse@moonhenge.net>
CC: "www-style@w3.org" <www-style@w3.org>
Message-ID: <07349ECFC3608F48BC3B10459913E70B12D13411@TK5EX14MBXC132.redmond.corp.microsoft.com>
On Sunday, August 01, 2010 2:46 PM Anton Prowse wrote:
> 
> 9.2.1 (Block-level elements and block boxes) says:[1]
> 
>    # Block-level elements (except for display 'table' elements, which are
>    # described in a later chapter) generate a principal block box that
>    # contains either only block boxes or only inline boxes.
> 
> 9.2.1.1 (Anonymous block boxes) says:[2]
> 
>    # In a document like this:
>    #
>    # <DIV>
>    #   Some text
>    #   <P>More text
>    # </DIV>
>    #
>    # (and assuming the DIV and the P both have 'display: block'), the DIV
>    # appears to have both inline content and block content. To make it
>    # easier to define the formatting, we assume that there is an
>    # anonymous block box around "Some text".
>    #
>    # In other words: if a block box (such as that generated for the DIV
>    # above) has another block box or run-in box inside it (such as the P
>    # above), then we force it to have only block boxes and run-in boxes
>    # inside it.
> 
> OK. But we also have the following from 16.6.1 (The 'white-space'
> processing model)[3] (which will likely be moved to Ch.9; see [4]):
> 
> 16.6.1:
>    # Any text that is directly contained inside a block element (not
>    # inside an inline element) should be treated as an anonymous inline
>    # element.
> 
> Issue 1:
> 
> Does that mean that there's an anonymous inline box around "Some text"
> or that there's one around "Some text <P>More text" (which would mean
> that the rules for breaking an inline box around a block then come into play)?
> In fact it doesn't matter, since we end up with an anonymous block
> containing an anonymous inline containing "Some text" in both
> interpretations.  But what if it were "Some text <SPAN>More text</SPAN>
> End text"?  In this case the two interpretations – anonymous inline boxes
> around "Some text" and "End text" or one anonymous inline box around
> everything – yield different results.
> 
> I think the sentence from 16.6.1 says that it's the first interpretation, in each
> case.  I'd be grateful for confirmation of that!
> 
> 
> 9.2.1.1:
>    # When an inline box contains a block box, the inline box (and its
>    # inline ancestors within the same line box) are broken around the
>    # block. The line boxes before the break and after the break are
>    # enclosed in anonymous boxes, and the block box becomes a sibling of
>    # those anonymous boxes. [...]
> 
> Issue 2:
> 
> s/contains a block box/contains an in-flow block box/
> 
> since containing a float doesn't cause the inline content to be split between
> two different blocks.
> 
> 
> Issue 3:
> 
> What /does/ happen when an inline box contains a float?  Does the run of
> inlines+floats in which it sits get wrapped in an anonymous block box
> which becomes the sibling of the floats?  If so, this needs stating.
> 
> 
> Issue 4:
> 
> Is it the case that, with the exception of an anonymous table box, an
> anonymous block box contains either only block boxes or only inline boxes,
> much like a principal block box?  (This is essentially the same question I'm
> asking in [5] as part of the great box cleanup; we'll need to ensure we get the
> same answer!)
> 
> 
> 9.2.1.1:
>    # This model would apply in the following example if the following
>    # rules:
>    #
>    # body { display: inline }
>    # p    { display: block }
>    #
>    # were used with this HTML document:
>    #
>    # <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
>    # <HEAD>
>    # <TITLE>Anonymous text interrupted by a block</TITLE>
>    # </HEAD>
>    # <BODY>
>    # This is anonymous text before the P.
>    # <P>This is the content of P.</P>
>    # This is anonymous text after the P.
>    # </BODY>
>    #
>    # The BODY element contains a chunk (C1) of anonymous text followed by
>    # a block-level element followed by another chunk (C2) of anonymous
>    # text. The resulting boxes would be an anonymous block box around the
>    # BODY, containing an anonymous block box around C1, the P block box,
>    # and another anonymous block box around C2.
> 
> Issue 5:
> 
> Why would there be an anonymous block box around the BODY?  Surely the
> principal block box of the (implied[6]) HTML is what surrounds the
> anonymous block box around C1, the principal block box of the P, and the
> anonymous block box around C2.
> 
> 
> [1] http://www.w3.org/TR/CSS2/visuren.html#block-boxes

> [2] http://www.w3.org/TR/CSS2/visuren.html#anonymous-block-level

> [3] http://www.w3.org/TR/CSS2/text.html#white-space-model

> [4] http://lists.w3.org/Archives/Public/www-style/2010Jul/0440.html

> [5] http://lists.w3.org/Archives/Public/www-style/2010Aug/0004.html

> [6] http://www.w3.org/TR/html5/syntax.html#optional-tags

> 

Thank you for your feedback. The CSSWG has addressed your concerns in the upcoming publication of the CSS 2.1 specification[1]. 

The CSSWG resolved to: Replace “The resulting boxes would be an anonymous block box around the P” with “The resulting boxes would be a block box representing the P”.

We hope this closes your issue.

Please respond before 18 March, 2011 if you do not accept the current resolution.

[1] http://w3.org/TR/CSS

Received on Wednesday, 16 March 2011 20:01:19 GMT

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