W3C home > Mailing lists > Public > www-style@w3.org > April 1996

Re: CSS and SGML document formatting

From: Bert Bos <Bert.Bos@sophia.inria.fr>
Date: Tue, 23 Apr 1996 00:37:50 +0200
Message-Id: <199604222237.AAA08582@mygale.inria.fr>
To: www-style@w3.org
Wolfgang Rieger writes:
 > Are there any specs / discussion materials / whatever concerning the
 > extension of CSS for the formatting of general SGML documents with
 > arbitrary DTDs?

We don't have any ambition to extend CSS to arbitrary SGML, though of
course we have no objection to it being used outside of HTML.

CSS is probably only useful for formats that are `similar' to HTML,
which means something like: it is a document that already contains all
the text the reader will see, and the text is already in the right
order (modulo things like floating images). The layout depends on the
element names and their nesting, not on their order (although we will
probably have to extend CSS a little in that direction.)

Making CSS suitable for other types of document will mean major
changes.

If it turns out that there are document formats that need important
reshuffling of elements, than a possible approach is to add a DSSSL
interpreter to the formatter; just the DSSSL tree transformer might be
enough.

 > In particular: Is there material on the extension necessary to
 > transport the semantics now implicit in HTML (e.g. BR is empty and
 > rendered as a line break, H1 is a heading, etc.)?

The fact that BR is empty cannot be found in the style sheet, but must
be extracted from the DTD. The fact that H1 is a heading is a semantic
notion that is too abstract for the style sheet. The style sheet can
only try to make the H1 more visible.

But there are indeed some implicit HTML dependencies in CSS: the
pseudo-classes link/visited/active assume some mechanism outside the
formatter; also images are implicitly classified as `replaced'
elements.

These dependencies can be easily removed. They will probably disappear
automatically as new features are added.


For DSSSL, see:

    http://www.w3.org/pub/WWW/International/obtainDSSSL.html

For DSSSL-online, a subset of DSSSL:

    http://occam.sjf.novell.com:8080/docs/dsssl-o/do951212.htm



Bert
-- 
  Bert Bos                                ( W 3 C ) http://www.w3.org/
  http://www.w3.org/pub/WWW/People/Bos/                      INRIA/W3C
  bert@w3.org                             2004 Rt des Lucioles / BP 93
  +33 93 65 77 71                 06902 Sophia Antipolis Cedex, France
Received on Monday, 22 April 1996 18:37:56 GMT

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