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

Re: Suggestion: A link model

From: David G. Durand <dgd@cs.bu.edu>
Date: Tue, 31 Dec 1996 13:11:52 -0500
Message-Id: <v02130503aeeeec172131@[]>
To: w3c-sgml-wg@www10.w3.org
At 2:43 PM 12/30/96, W. Eliot Kimber wrote:
>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.

I agree that it is a much more fortunate and natural syntax for fixed
anchor roles.

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

Sure, in fact, I think we could easily make agglink work for both cases:
  Add back and anchrole attribute to agglink, and require that it contain
at least one role. Add a rule stating that if the agglink has more anchors
than anchor roles, then the last role applies to all the anchors whose
locations are expressed last. You can think of this as an "anchor model"
where the last anchor role has an implicit * on it. Of course it would be
nice if there were a way to to integrate this with the clink/ilink
distinction. One way would be to say the any content of an agglink is an
anchor like a clink's but if the content model is EMPTY, then it functions
link an ilink. I don't know if this kind of case-switching is part of the
HyTime meta-language, but it's not too complicated.

   -- David

I am not a number. I am an undefined character.
David Durand              dgd@cs.bu.edu  \  david@dynamicDiagrams.com
Boston University Computer Science        \  Sr. Analyst
http://www.cs.bu.edu/students/grads/dgd/   \  Dynamic Diagrams
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Received on Tuesday, 31 December 1996 13:05:24 UTC

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