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Re: bidi discussion list was: Bidi Markup vs Unicode control characters

From: Bert Bos <bert@w3.org>
Date: Tue, 9 Aug 2005 01:30:52 +0200
To: www-international@w3.org
Message-ID: <20050808233052.GA7207@mygale.sophia.w3.org>

On Mon, Aug 08, 2005 at 01:13:49PM -0700, Tex Texin wrote:
> Sandra, yes of course. I am not suggesting CSS be made a requirement for
> bidi. Only that it should be acceptable and considered best practice in
> the right context.
> At the time the standard was written, I took the warning that bidi css
> may be ignored by user agents to be a reflection of the state of the art
> at the time, since most browsers were not able to support bidi with or
> without css.

As Fantasai said, it is a design goal of CSS that CSS can be turned
off without affecting the meaning of the document (first bullet of
section 2.4 http://www.w3.org/TR/CSS21/intro.html#q6).

It's sometimes a difficult goal to follow. For example, generic XML
doesn't have hyperlinks and it would be quite simple to create a
property in CSS to make elements into hyperlinks. Such a property has
been tested in practice and it doesn't need to be very complex to be
very useful. But so far we are hoping for a solution outside CSS.

Bidi properties are similar, but there we have gone the other way:
generic XML doesn't have bidi attributes and nobody was even talking
about adding them (unlike for links, where XLink has been attempted),
so we had no choice but to add bidi properties to CSS.

That's why CSS (in section 9.10
http://www.w3.org/TR/CSS21/visuren.html#direction) indeed tells people
not to use these properties. In general, creators of an XML-based
format should tell how the elements/attributes of their formats map to
CSS 'direction' & 'bidi-override' properties and other people should
not override them.

> It had not occurred to me that people were interpreting it to mean that
> css implementers would intentionally choose not to support it or that
> W3C was endorsing such a view. That would be counter to goals for
> internationalization and making the web accessible to all.

The CSS2 spec used to say that a program was allowed to ignore the
properties in the case of HTML documents, but it doesn't say that
anymore. There is no difference anymore between HTML and XML in that

Individual profiles can still say which properties are optional and
both the Mobile Profile and the Print Profile say the bidi properties
are not required for conformance. I believe that is because both
profiles are in practice only used with XHTML1 and thus the properties
aren't needed.

  Bert Bos                                ( W 3 C ) http://www.w3.org/
  http://www.w3.org/people/bos                               W3C/ERCIM
  bert@w3.org                             2004 Rt des Lucioles / BP 93
  +33 (0)4 92 38 76 92            06902 Sophia Antipolis Cedex, France
Received on Monday, 8 August 2005 23:30:58 UTC

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