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Re: Formatting Objects considered harmful

Subject: Re: Formatting Objects considered harmful
From: "Fredrik Lindgren" <f.lindgren@xxxxxxxxxx>
Date: Fri, 16 Apr 1999 17:05:24 +0200

Reading this document helped me understand why some people don't want to
split XSL into separate parts XTL and XFO. (It's not the use of XTL
alone that is dangerous, it is the use of XFO alone that is)

At the end of the document Håkon outlines some ideas to avoid disaster.
I'd like to comment on one of them. It's the last one where it is
suggested that formatting objects should not be expressed in XML.

In the XSL draft the following text in the overview states:
"When the result tree uses the formatting vocabulary, a conforming XSL
implementation must be able to interpret the result tree according to
the semantics of the formatting vocabulary as defined in this document;
it may also be able to externalize the result tree as XML, but it is not
required to be able to do so."

As I see it, the real problem is that we don't have formalism to use to
specify the "semantics of the formatting vocabulary" yet. This means
that we can only specify it using the syntax. I guess what is really
needed is the forthcoming work of the Information set working group. By
defining what is passed between the XTL processor and the XFO renderer
using the information set would be better than the current situation

Please hurry David!  (Megginson who chairs the information set group)

It's not a coincidence that DSSSL is specified using groves instead of
SGML document syntax. 	/at least I don't think it was a coincidence.

Fredrik Lindgren
Upright engineering AB

Håkon Wium Lie wrote:
> I've put some thoughts about Formatting Objects on the Web into
> writing [1]. Here's the abstract:
>   The W3C Working Group on XSL is currently producing two
>   specifications: a transformation language (called "XTL" in this
>   document) and a set of formatting objects written in XML (called
>   "XFO" in this document). The idea is for XTL to transform XML data
>   and documents into set of formatting objects which subsequently can
>   be rendered. On the ladder of abstraction from presentation to
>   semantics, XFO is at the level of presentational HTML elements. A Web
>   of XFO documents can be compared to a Web of HTML documents with only
>   FONT and BR tags. Although not intended to be used on the Web, it's
>   unlikely that it can be prevented. XFO is therefore a threat to
>   accessibility, device-independence and the dream of a semantic Web.
>   The note ends with some suggestions on how to solve the problem.
> [1] http://www.operasoftware.com/people/howcome/1999/foch.html
> -h&kon
> Håkon Wium Lie             http://www.operasoftware.com/people/howcome
> howcome@xxxxxxxxxxxxxxxxx                      simply a better browser
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