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Re: A possible presentational hints proposal for CSS 2.1

From: Stuart Ballard <sballard@netreach.com>
Date: Tue, 08 Oct 2002 12:37:51 -0400
Message-ID: <3DA309DF.4080907@netreach.com>
To: Chris Lilley <chris@w3.org>
CC: www-style@w3.org, Ian Hickson <ian@hixie.ch>, Rijk van Geijtenbeek <rijk@iname.com>

Chris Lilley wrote:
> On Tuesday, October 8, 2002, 5:28:07 PM, Stuart wrote:
> 
> 
> SB> Why not enumerate the "standard" presentational attributes, and then say 
> SB> that additionally, all attributes not defined in the relevant 
> SB> specifications are presentational? That way any new attributes that get 
> SB> added to standard HTML are treated as non-presentational.
> 
> Since this text differentiates between HTML and XHTML, we can clearly
> say that the number of new attributes that get added to standard HTML
> will be zero.

True, I suppose. I stand by the theory that if you're going to treat 
non-presentationalness as a universal default, you should list the 
specific exceptions to that default, rather than say "in this particular 
situation, everything *except* these things are exceptions".

But since you seem to be advocating *not* making it a universal default, 
the list can be stated either way.

> SB> May I suggest including language that allows other XML vocabularies to 
> SB> explicitly designate attributes as presentational if they want to?
> 
> 
> Such as, for example, languages that are themselves presentational?
> That would be a lot better than merely looking at HTML and deciding
> that all XML has no presentational attributes.
> 
> Rather than talk about 'transitional phases' and so forth, i suggest:
> 
> a) distinguishing between presentational and non-presentational XML
> grammars. For example, MathML has two grammars, one of each type.
> 
> b) stating that non-presentational grammars should not have, or add,
> presentational attributes.

Unfortunately, as you point out later, this doesn't fit with several 
already-existing XML vocabularies.

> c) stating that presentational attributes should have the exact same
> name, syntax, and semantics as the corresponding property. They then
> become zero-specificity "default styling" which is readily "restyled"
> by any CSS selector. this is, for example, the case in CSS.

I'm not sure that all attributes in classic HTML can be shoehorned into 
this rule. Are you?

> While being more realistic and less antagonistic to other W3C
> specifications, this approach also - by encouraging use of stylistic
> attributes, rather than the style attribute, for presentational
> grammars - encourages restylability. Currently, lots of tools that
> construct content incrementally spit out xml elements with style
> attributes on each element. Due to the high specificity of the style
> attribute, this makes later restyling hard in CSS2 and impossible in
> CSS 2.1

I agree with this reasoning, but I'm not going to go into it because 
it's a tangent from the issue at hand. I hope that the W3C eventually 
agrees with this and comes up with a solution, though :)

> Presentation attributes are not just a legacy issue.

Point.

> SB> Thus, I'd suggest treating XHTML Transitional as
> SB> HTML,
> 
> No!! Its XML, uses the XML Object Model, etc. Don't muddy things
> further by treating some XML as HTML.

I meant "in the same way as the proposal currently treats HTML", not 
"pretend that it *is* HTML".

> SB>   For other XML languages where the document type or schema
> 
> or namespace (for namespace qualified attributes)

Point.

> This is where I really wish that the presentation attributes in XSL
> (and in SVG) had been defined in their own namespace. I still think
> that would have been a better solution.

I agree, but since they're not, we need a solution for those existing 
specs. And, of course, for XHTML Transitional, which falls into the same 
category (some presentational and some semantic attributes).

I think my language (with your specific proposed additions, such as the 
namespace issue) could cover MathML, XSL-FO and SVG perfectly well. In 
fact, the treatment of classic HTML (and what I proposed for XHTML 
Transitional) is really just part of the same thing, except that the use 
of CSS with HTML is so ubiquitous that it makes sense for the CSS 
authors to explictly list the presentational attributes for that language.

The only difference is that now the treatment of presentational 
attributes is no longer just a legacy issue, but since the proposed 
language never mentioned "legacy" at all, the bulk of it still stands.

Stuart.

-- 
Stuart Ballard, Programmer
NetReach - Internet Solutions
(215) 283-2300, ext. 126
http://www.netreach.com/
Received on Tuesday, 8 October 2002 12:38:00 GMT

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