W3C home > Mailing lists > Public > w3c-sgml-wg@w3.org > December 1996

Re: Suggestion: A link model

From: W. Eliot Kimber <eliot@isogen.com>
Date: Mon, 30 Dec 1996 14:43:51 -0900
Message-Id: <3.0.32.19961230143902.00c03198@uu10.psi.com>
To: dgd@cs.bu.edu (David G. Durand), w3c-sgml-wg@www10.w3.org
At 03:10 PM 12/30/96 -0500, David G. Durand wrote:
>At 11:11 AM 12/30/96, W. Eliot Kimber wrote:

[...]

>> Thus, we provide the
>>agglink form which lets you relate an unlimited number of things together
>>without first defining a distinct role name for each.
>
>What if I want to dfine distinct role names for each, but not in advance?
>That is the feature request, and blusterung about link types does not
>change the answer that you are giving "No, because _we believe_ that it is
>not what yolu really want."

I think I understand David's feature request.  We have certainly discussed
the issue of variable anchor roles at some length during the TC design, but
it was usually in a difference context which I don't think is as well
justified as David's.

I see also that this is a primary point of potential failure in trying to
design an XML linking approach that happens to also be HyTime conforming.

>This is truly unfortunate. The original design was susceptible of
>improvement, this one is not. XML should define a mechanism for assigning
>anchroles to the endpoints of an agglink, in that case, and maybe the
>HyTime committee will see fit to include it.
>
>In fact, I think the solution I proposed will still work, but just won't be
>HyTime compatible any more, since HyTime is too inflexible to accomodate
>it. Can we make agglink equivalents of both clinks and ilinks?

It would certainly be possible for XML to use the agglink form and then
define an XML-specific way to associate anchor roles with members of the
aggregate, but that would be a hack--it would be better to fix the design
at its core (which has been David's point all along, of course).

This will take some careful thought, but there might be a way to make it work.

I should point out that I think the new hylink syntax, where each role has
its own addressing attribute is much easier to use and explain than the old
ilink syntax, where you had to explain (and validate) the positional
correspondence between anchor roles and anchor addresses (complicated by
the fact that indirect addressing could obscure what was being
addressed--you didn't just count IDs in the linkends attribute value).  The
feature David wants would require the ilink-style addressing syntax with a
single attribute for all the link ends--a syntax that in my experience of
teaching HyTime is a difficult one for people to use.

Let me also ask this: do we agree that when we *don't care* about anchor
roles, that an aggegate link is sufficient?

Cheers,

E.
--
W. Eliot Kimber (eliot@isogen.com) 
Senior SGML Consulting Engineer, Highland Consulting
2200 North Lamar Street, Suite 230, Dallas, Texas 75202
+1-214-953-0004 +1-214-953-3152 fax
http://www.isogen.com (work) http://www.drmacro.com (home)
"Rats in the morning, rats in the afternoon...if they don't go away, I'll be
re-educated soon..."                 --Austin Lounge Lizards, "1984 Blues"
Received on Monday, 30 December 1996 16:45:49 EST

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