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Re: [CSS21] Does 'clear' apply to caption box? (corrected link)

From: Daniel Schattenkirchner <schattenkirchner.daniel@gmx.de>
Date: Tue, 08 Jan 2013 16:48:44 +0100
Message-ID: <50EC3FDC.2060103@gmx.de>
To: www-style@w3.org
> I believe this test
> http://test.csswg.org/suites/css2.1/20110323/html4/clear-applies-to-015.htm
> may be incorrect.


> which would mean that clear can/could apply to an element with its
> display property set to 'table-caption'. So, at least the meta text
> assert isn't completely true.

I'd agree, since table-captions are block-level boxes (to which clear 

CSS 2.1, 9.5.2: http://www.w3.org/TR/CSS21/visuren.html#flow-control
> Applies to: block-level elements

CSS 2.1, 17.4: http://www.w3.org/TR/CSS21/tables.html#model
> The caption boxes are block-level boxes ...

At this moment, however, it's not possible test whether a browser conforms.

>> Note that if you had two captions in a CSS-styled table (something
>> which is invalid in HTML4 tables), you could float both of them
>> left and set "clear:left" on the second one, to observe that
>> 'clear' does apply to table captions... although it isn't a very
>> useful design pattern so I don't imagine authors do it much!

A floated table-caption is a display: block; box and not part of 
anonymous table box generation. And even tough CSS does allow 
consecutive caption boxes, they are not supported by Gecko and WebKit.

> 17.2.1 Anonymous table objects
> http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes
> states that an anonymous 'table' (or 'inline-table') box T must be
> generated for misparented 'table-caption' box... and so, it seems,
> this implies that it does not create an anonymous table wrapper
> box...

A table box generates a table wrapper box according to CSS 2.1, 17.4:
> In both cases, the table generates a principal block box called the
> table wrapper box that contains the table box itself and any caption
> boxes (in document order).

> Anton, this is your scenario-example:
> http://www.gtalbot.org/BrowserBugsSection/css21testsuite/clear-applies-to-caption-boxes-2.html
>  I'm still a bit confused by all this.

It's impossible to create a testcase to test whether clear really does 
apply to table-captions.

A table-caption is always wrapped in a table wrapper box.
A floated table-caption is actually display: block; see CSS 2.1, 9.7: 

There can't be any element between the table wrapper box and a table 
caption except other table elements. Floats become wrapped in 
table-cells (or are not wrapped at all like in your testcase 2).

In Gecko, you could try to test the caption-side: left, right, 
top-outside and bottom-outside which emulate CSS 2 behaviour of captions 
(but are currently not specced). But IIRC their implementation still 
places the caption inside the table wrapper box. I.e. you still couldn't 
create a test (or you could say they don't emulate CSS 2 correctly, but 
thats not seizable).

Daniel Schattenkirchner
Received on Tuesday, 8 January 2013 15:49:12 UTC

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