[6250] in www-talk@info.cern.ch
Re: Format Negociation in Practice [Was: Versioning HTML at the server]
daemon@ATHENA.MIT.EDU (Joe English)
Wed Oct 19 13:35:25 1994
Date: Wed, 19 Oct 1994 17:53:38 +0100
Errors-To: postmaster@www0.cern.ch
Errors-To: postmaster@www0.cern.ch
Reply-To: jenglish@crl.com
From: Joe English <jenglish@crl.com>
To: Multiple recipients of list <www-talk@www0.cern.ch>
Earl Hood <ehood@imagine.convex.com> wrote:
> [jenglish@crl.com wrote:]
> > How about parameters on the Accept: header?
> > [...]
> > This should require a minimal change to browsers,
> > as the HTML features supported by a browser are
> > more or less fixed.
>
> The main problem I see with this solution is that it is HTTP specific.
> HTML is an SGML application. I believe it is best that a solution is
> targeted more in the SGML realm so authors have more control on how a
> document will appear based upon a client's conformance level.
Browser support for marked sections is clearly
desirable, for this and other reasons. I'm
not holding my breath though; two of the three
browsers I use don't even get comment declarations
right yet.
> Plus not
> all HTML documents are served via HTTP.
True, but I don't think that's too big an issue.
Forms, imagemaps, and indexes don't work over
anything but HTTP either.
> Here's where I think it would be better if authors could state in the
> document itself what alternatives should be used based on a clients
> capabilities. For example, an author might want a list to be used in
> place of a table for clients w/o table support, instead of the table
> being converted to a <PRE> construct.
This is desireable, but authors mustn't be required
to write and maintain both versions of the table.
How about something like this:
<!-- in the prolog, declare which features the document uses: -->
<?HTML FEATURE tables>
<?HTML FEATURE forms>
<?HTML FEATURE imagemaps>
<HTML>
...
<h3>Table 1</h3>
<?DOWNGRADE table pre>
<table>
<!-- a complex table with spanning columns, header and footer rows;
to be converted to <PRE> for browsers that don't grok tables.
The <?DOWNGRADE> PI is an instruction to the server-side
conversion filter.
-->
</table>
<h3>Table 2</h3>
<?DOWNGRADE table dl>
<table>
<!-- table 2 is a simpler, two-column table;
to be downgraded to <DL>
-->
</table>
..
</HTML>
--Joe English
jenglish@crl.com
