[whatwg] Significant inline content vs. attributes and sectional elements

Ian Hickson ian at hixie.ch
Thu Mar 9 14:08:25 PST 2006

On Thu, 9 Mar 2006, Henri Sivonen wrote:
> It seems to me that the WA 1.0 spec presents requirements on document 
> conformance that are very different from each other in spirit in a 
> seemingly arbitrary way.
> On one hand, some elements are required to have significant inline 
> content or are barred from having traditional flow content while, on the 
> other hand, the requirements on attribute occurrence are very lax and 
> sectional elements are not required to have any content at all. These 
> requirements seem very inconsistent in spirit to me.

Yeah, I haven't really thought these through yet.

Here are some of the things I'm worried about:

 * It should be possible for scripts to add content to placeholder 
   elements without those placeholder elements being non-conformant.
   This is a very useful programming idiom, not least of which because
   adding content to an existing element (whether attributes or child
   nodes) is a lot easier than adding the element in the first place.

 * It should be possible to have a group of pages that have a similar 
   structure, with elements annotated as necessary. For example, a menu
   list could be the same on each page, but with the currently loaded
   page simply not having the "href" attribute on its link, or some such.

 * It should always be clear from a semantic point of view whether the
   content is a single "paragraph", or whether it is a group of 

> To make document conformance a more useful concept for the purpose of catching
> author errors, I suggest that the following attributes be made required:
> href and rel on link
> href on base
> name and content on meta (other than the encoding decl)
> src on img
> code, height and width on applet
> name and value on param

I've made a note of this in the draft so I don't lose track of it. Your 
proposals make sense on the whole. Exceptions: <base target> may mean that 
<base> should have either href or target. <img> might be a placeholder, 
I'm still considering exactly what we want with that one.

> To allow user agents see whether the author provided the empty string as the
> alternative text of whether the author just didn't care, I suggest that the
> alt attribute on img be made optional.

I agree.

> Since sectional elements are document-oriented rather than Web 
> application-oriented, it seems to me it would make sense to require them 
> to contain one or more block elements as opposed to zero or more.

You can have empty sections. They might not be written yet, for instance.

> On the other hand, I have doubts about the requirement of significant 
> inline content. When the W3C said that paragraphs mustn't be empty, 
> various applications started emitting <p> </p>. If the WHAT WG says 
> that paragraphs must contend significant inline content, are the 
> developers of those applications suddenly going to decide not to allow 
> them to paragraphs to be saved or are they going to come up with an even 
> more crufty work-around to comply with the machine-checkable 
> requirements of the spec?

I agree. I think I'll remove mention of the "significant inline content" 

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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