Re: Alternate source tags?

Daniel W. Connolly (
Wed, 01 May 1996 00:59:17 -0400

Message-Id: <>
To: Jim Taylor <>
Subject: Re: Alternate source tags? 
In-Reply-To: Your message of "Mon, 29 Apr 1996 18:50:37 -0800."
Date: Wed, 01 May 1996 00:59:17 -0400
From: "Daniel W. Connolly" <>

In message <>, Jim Taylor writes:
>It would be nice if there were a mechanism for specifying secondary
>sources anywhere a SRC or HREF attribute can appear, something like

Yes, this functionality is interesting... but:

Please! No! Not those idioms!

First, you can do this in the browser implementation. I think
Spyglass and Verity do this already: they just use the CD-ROM
as a cache. To fetch, they first
check the CD ROM's cache table. If it's there, the get it
locally. If not, they attempt to go the net. (Maybe they
do if-modified-since queries sometimes... anyway...)

The point is that you can get the behaviour you want without
changeing HTML, if you control the browser. Since you're talking
about features that aren't in the installed base of browsers,
you're going to have to do that anyway, for a while.

But the business of describing replicas and other interesting
sorts of link info in HTML is useful in many other situations.

It's seen as "the missing link" in the format negotiation
strategy, for example.

I don't really have time to explain fully, but...

Please see the following unpublishded draft:

Giving Information About Other Resources in HTML
	W3C Scribbled Draft 20-Nov-95
	Tim Berners-Lee <>, Dave Raggett <>