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Re: Serving generic XML (was: storing info in XSL-FO: new issue?)

From: Jan Roland Eriksson <jrexon@newsguy.com>
Date: Mon, 19 Aug 2002 20:41:32 +0200
To: www-tag@w3.org, www-style@w3.org
Cc: Svgdeveloper@aol.com, kynn@idyllmtn.com
Message-ID: <qte2muo846415p99navioj873p45ujm5eh@4ax.com>

On Mon, 19 Aug 2002 00:36:18 -0700 (PDT), Kynn wrote:

[... fup's narrowed ...]

>WCAG 1.0, checkpoint 6.1:
>http://www.w3.org/TR/WCAG/#gl-new-technologies
>
>6.1 Organize documents so they may be read without style sheets...

That is impossible. All kinds of rendering needs some form of stylesheet
to suggest a presentational, and to humans recognizable connection,
between element markup/content and an available NOTATION for a defined
markup system (e.g. (X)HTML) [1].

>    For example, when an HTML document is rendered without associated
>    style sheets, it must still be possible to read the document.

And that can only be done if the user agent still is in posession of
e.g. a basic ua.css that can never be turned off.

Programmers of special kinds of clients like indexing robots can make
use of the NOTATION for a markup system to find out how to give
different index weight to various parts of content in an instance, but
what they are doing at that point is in fact nothing but writing a
special type of stylesheet that the indexer needs to be able to "render"
the instance for it self.

>It is not possible to "read" (understand) arbitrary XML without a
>stylesheet; it is (to the UA) a collection of tags without semantics.
>(This is different from the case of XHTML, which is not arbitrary
>XML.)

Without an appropriate and fixed user agent stylesheet even (X)HTML
would be rendered totally meaningless in a "common" user agent.

As seen from that point, all ua's produced ever, have been conforming to
a CSS spec that in fact came on in later time.

From CSS1, sections...

  1 Basic concepts
  HTML authors need to write style sheets only if they want to suggest
  a specific style for their documents. Each User Agent (UA, often a
  "web browser" or "web client") will have a default style sheet that
  presents documents in a reasonable -- but arguably mundane -- manner.
  Appendix A contains a sample style sheet to present HTML documents as
  suggested in the HTML 2.0 specification [3].

  7 CSS1 conformance
  A UA does not have to implement all the functionality of CSS1: it can
  conform to CSS1 by implementing the core functionality. The core
  functionality consists of the whole CSS1 specification except those
  parts explicitly excluded. In the text, those parts are marked with
  "CSS1 core:" followed by an explanation of what functionality is
  outside the core functionality. The set of features excluded from the
  core functionality is called CSS1 advanced features.
  .
  This specification also recommends, but doesn't require, that a UA:
  * allows the reader to specify personal style sheets
  * allows individual style sheets to be turned on and off

That last point indicates to me that even e.g. a ua.css shall be allowed
to be turned on and off (it is an "individual" stylesheet, no?), in
which case the semantic hints buried in pure presentation would be
totally lost even for (X)HTML.

[1]
<http://groups.google.com/groups?selm=gbksat4allprkepjv69nv93ckqoqecgr41%404ax.com&rnum=5>

-- 
Rex
Received on Monday, 19 August 2002 14:43:37 GMT

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