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Re: [CSS21] Unclear applicability to XML

From: Chris Lilley <chris@w3.org>
Date: Mon, 29 Aug 2005 16:49:08 +0200
Message-ID: <1737217871.20050829164908@w3.org>
To: Ian Hickson <ian@hixie.ch>
Cc: www-style@w3.org

On Sunday, August 28, 2005, 7:16:48 PM, Ian wrote:

IH> On Thu, 25 Aug 2005, Chris Lilley wrote:
>> The abstract says that CSS 2.1 is for "to structured documents (e.g., 
>> HTML documents and XML applications)" but then removes items (relative 
>> to CSS2.0) such as @font-face because they have not been implemented in 
>> HTML browsers, regardless of whether they have been implemented with XML 
>> applications.
>> http://www.w3.org/TR/2005/WD-CSS21-20050613/
>> and yet later it says
>>    CSS2.1 aims to reflect what CSS features are reasonably widely
>>    implemented for HTML and XML languages in general (rather than only
>>    for a particular XML language, or only for HTML)
>>    http://www.w3.org/TR/2005/WD-CSS21-20050613/about.html#q1

IH> The implementations of @font-face we found were either very incomplete 
IH> implementations or implementations that only implemented very limited 
IH> subparts of CSS (such as only the parts required by SVG).

And yet no attempt was made to place those parts implemented in SVG user
agents into CSS2.1, calling into question yet again whether CSS 2.1 is
aimed at HTML user agents exclusively, or aimed at other uses of CSS as

IH>  Our CR exit
IH> criteria requires significantly better implementations than were available
IH> for @font-face as far as we could tell.

For the whole thing, or for the subset that is useful and implemented?

IH>  In addition, we have neither a
IH> decent test suite for @font-face nor any volunteers to write one, which 
IH> would be another problem with moving @font-face through to REC in CSS2.1.

The same applied to most of CSS 2.1, which until recently had only a
copy of the CSS1 tests and no CSS2 tests at all.

IH> The @font-face feature in CSS2 is still in CSS2, and is also covered by a
IH> CSS3 spec for which, if I am not mistaken, you are the editor. Therefore
IH> we do not see any difficulty in the removal of this feature.

There is a certain 'difficulty' in having RECs that used to
point to RECs now point to unstable working drafts.

IH> CSS2.1 is intended for applications that style structured documents, be 
IH> they based on SGML or XML or another tree-based format. However, our 
IH> primary concern is with full implementations of CSS,

Please define that term.

IH>  not implementations
IH> of subparts of CSS required by other specifications,

Such as CSS Print or CSS Mobile profile?

IH>  as it is the
IH> complete implementations that will help us exit CR. (It doesn't really 
IH> matter if we have interoperability on one half of the spec in one set of
IH> UAs and another half of the spec in another set of UAs -- that would be 
IH> pretty worthless for Web authors!)

Certainly. Although, if the two sets of UAs were disjoint then having
two specifications, each of which defined the half that a set of UAs
used, would be of value.

IH> Your comment did not make any specific requests; please let us know if the
IH> above explanations answered your feedback or if you would like us to make
IH> specific changes.

The specific request is to

a) clarify whether CSS2.1 is aimed at:
 1) HTML 4.x user agents only
 2) HTML 4.x and XHTML user agents (collectively, (X)HTML only)
 3) A variety of user agents, including (X)HTML, SVG,
 4) A wide variety of XML and (X)HTML user agents including MathML, DocBook,
 CML etc etc

b) Justify the choice of language features (@rules, properties, etc)
based on the response to a)

In other words, please ensure the aim, scope and applicability of CSS2.1
to XML is very clear. It is currently unclear.

 Chris Lilley                    mailto:chris@w3.org
 Chair, W3C SVG Working Group
 W3C Graphics Activity Lead
Received on Monday, 29 August 2005 14:49:25 UTC

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