[whatwg] <hgroup> functionality absorbed into <header>?

[Kornel Lesinski]

On Sun, 18 Oct 2009 08:54:59 +0100, Ian Hickson <ian at hixie.ch> wrote:

>> Your version with split <h2> seems to use it only for visual effect.
>
> Not just visual, but presentational, yes, pretty much. It also makes it
> clear how to generate the outline.

I don't understand how presentational <h2>s make outline clear. I thought  
they're an exception that didn't work simple outline algorithm:

http://validator.w3.org/check?uri=http%3A%2F%2Fwww.w3.org%2FTR%2Fhtml5%2F&outline=1#outlineresult

and <hgroup> exists to resolve ambiguity caused by presentational use of  
headers.

>> I still think that <subtitle> (subheader, tagline) would be just as
>> effective, less confusing and less likely to break outline when used
>> improperly...
>
> How is <h2> confusing?

<h2> alone isn't. <hgroup> is the source of confusion.

* Difference between <hgroup> and <header> is not obvious. It wasn't to me  
when I first saw them, and this isn't first thread about them.
* Makes meaning of <hx> overloaded (sometimes it's a header that affects  
outline and level or other headers, sometimes it's a subheader that  
doesn't do anything that header would).

Have you seen this post? http://www.onderhond.com/blog/work/the-hgroup-tag  
I think it sums up problems quite well.

> I think something like <subtitle> is just as likely to be misused as  
> <hgroup>, to be honest.

Sure, but it's much more fail-safe. If you use <header> instead of  
<hgroup> or fail to use <hgroup>, you may significantly change structure  
of the document.

You can't make much damage with <subheader>. Sections will remain correct  
and at worst you'll add wrong subtitles to headers.


My proposal for processing of <subheader>:

* look for first <hx> preceeding <subheader> in tree order (depth-first  
starting with last child) [makes any <subheader> after <hx> work]
* abort and ignore subheader when search crosses section boundaries  
[prevents misplaced <subheader> from being associated with wrong section].

Optionally:
* if <hx> is an ancestor of <subheader>, associate subheader with that  
header

The last rule allows:

<h1><subheader>The magnificent</subheader> HTML 5 specification</h1>

which addresses one of use cases you've mentioned a while ago when  
<hgroup> was discussed.

> Also, it has a much poorer legacy (backwards compatibility) story.

Both solutions have problems. I don't think ones are much worse than the  
others. <hgroup> breaks the outline, <subheader> is ignored. Without CSS  
<h2>s will be too large and have too big margins. <subheader> will not get  
special rendering, but at least will look like block element (<hx> and <p>  
typically surrounding it will cause this). One might use <p><subheader><b>  
if non-CSS display is a concern.

With CSS <subheader> will work fine and doesn't limit styling  
possibilities. <hgroup>'s content model doesn't allow any non-header  
elements, so one can't add any extra hooks for styling:

<hgroup>
   <h1/>
   <div><!-- add fancy border around subheaders? -->
     <h2/>
     <h2/>
   </div>
</hgroup>


Another thing - can you write XPath query that extracts all headers from  
the document? Without <hgroup> it's simple. With <hgroup> I'm not sure if  
I could manage to write correct query.

-- 
regards, Kornel Lesinski