Re: style sheets for Arena

| Scott Bigham writes:
| > >- There has not been much public disussion on the latest CSS
| > >draft. [...]
| > 
| > Oh?  Well, there are a few comments I've been meaning to make, so if
| > the list will indulge me, I'll take this opportunity.
| > 
| > >  - add support for user-selectable multiple style sheets through the
| > >    TITLE attribute of the LINK element. Turning on/off various style
| > >    sheets should be under the interactive control of the user.
| > My main interest in multiple style sheets is that in the potential
| > eventuality of multiple co-existing style sheet notations (which we now
| > have, sort of, with the two existing versions of the CSS draft), page
| > authors might write the same style information in multiple notations for
| > maximum coverage.  It might be useful in that event to have a way to tell
| > the rendering agent that "These three <LINK REL=STYLE>'s all contain the
| > same information; once you've successfully parsed one of them, you can
| > ignore the others."  It might also be useful to be able to identify the
| > style sheet's notation in the <LINK> so that the rendering agent could
| > easily skip style sheets in notations it couldn't parse.
Date: Fri, 8 Sep 95 19:07 PDT
From: wmperry@spry.com (William Perry)
|   I would say this is the perfect place for HTTP content negotiation. When
| emacs-w3 requests a stylesheet, it only sends the Accept headers:
| Accept: application/stylesheet ; notation=experimental
| Accept: application/stylesheet ; notation=w3c-style
| Accept: application/stylesheet ; notation=css
| Accept: application/stylesheet ; notation=dsssl-lite

There is a new draft out in the MIME SGML working group that may be
of some use here.  The draft is about exchanging SGML documents using
catalogs and MIME.  I think the catalog part is useful here.  The
catalog contains references to document components.  One type of document
component is called Semantics which can be used for passing references
to notations.  From the draft:

   2.1.7 SEMANTICS

   There may be semantic information, such as stylesheets, associated with 
   a document.  Semantic information is not required to parse the document 
   and can be ignored by the client.  However, it is often required that a 
   client be able to access appropriate semantic specifications.  The 
   syntax for the SEMANTICS keyword is:

     semantics = ("SEMANTICS",   
        ps+, semantic name, ps+, semantic type, ps+, 
        storage object identifier) 

   Here's an example of an entry in a catalog for semantic information:

     SEMANTICS "large-print"  "DSSSL" 

The server references as many style sheets as it likes in the catalog and
the client references the one(s) it wants.  The server could make use
of http accept fields when building the catalog.  

The draft is not part of the IETF draft library yet (I'm having some 
difficulty moving the doc from Word into the IETF text format).
You can still get a copy of the draft via anonymous ftp at ftp.ebt.com. 
Change directory to pub/nv/mimesgml.  The ascii version of the doc
is catalogs.txt and the postscript version is called catlogs.ps - I suggest
looking at the postscript version.

Hope this is useful,