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Re: Relationship Taxonomy Questions

From: Paul Prescod <papresco@calum.csclub.uwaterloo.ca>
Date: Wed, 22 Jan 1997 21:44:53 -0500 (EST)
Message-Id: <199701230244.VAA09184@calum.csclub.uwaterloo.ca>
To: tallen@fsc.fujitsu.com (Terry Allen)
Cc: eliot@isogen.com, tallen@fsc.fujitsu.com, w3c-sgml-wg@www10.w3.org
> ?  I need to be able to specify the behaviors that Len's MID example
> did (and did quite independently from its specification of relationships):
>   traversal ( gosub | spawn | goto ) 
> I need to know those behaviors will work interoperably, and I cannot
> rely on applications that "provide their own behavior specification".
> If the ERB thinks that's going to work, I ask it to reconsider.  And
> I need whatever syntax is required to support specification of
> those behaviors (perhaps none at all).  I can already specify 
> relationship labels if I wish.

You need to be able to make a gosub happen, just as document authors need
to be able to make a "large heading" happen. But "the SGML way" (as you know
better than anyone) is to think about the structure of the document before
thinking about the "formatting behaviours" you intend to apply to it. Why
not the same with linking behaviours?

If we follow the formatting analogy to its conclusion, linking would be
done by a processing specification, (stylesheet) just as formatting is.
Which would mean that linking behaviour is part of our next section, not
this one. (Maybe...the definition of stylesheet is vague enough to do it now 
or then).

> The user cannot change the semantics of an HTTP URL, nor can he change
> the semantics of HTML's A element.  

Semantics, no. Behaviour yes. A user could specify that "A" links are green,
intead of blue. And when they are clicked on they are downloaded, but not
displayed. In fact a web walker is a "user agent" that *does* implement
link behaviour significantly different than a browser.

>If XML specifies 
>   traversal ( gosub | spawn | goto ) 
> and that XML apps have to respect those semantics to be conformant,
> the user will not be able to change the behavior of my document
> in an XML app.  

But what about the web-walker? Web-downloader? Search agent? Aren't those
user agents? Can't they change the behaviour? What about tools that show
you tables of contents for documents and their links. Can't I randomly
choose a document from my "site link map" rather than going through a page
and executing the "goto?"

As far as whether we should specify some relationships up front, I have two

#1. Maybe HyTime would be more widely used if it were less Meta and more 
language. That sounds like a slam against HyTime but it isn't. Scheme might
be more widely used if it were less functional and more like Java, but then
it wouldn't be useful for the important uses it is used for (whew!), like
DSSSL. Maybe XML is where we take HyTime to the masses by being a little
less meta.

#2. HTML left the link relationships "wide open" and we are still waiting for 
people to decide on the relationships.

I don't see a problem with <-XML-GOTO> or <-XML-STYLE-SHEET> or 
<-XML-NEXT-DOCUMENT>, etc. *Maybe* we could specify them in an appendix,
or another document, but I think that they should be specified by this 
group. I would not have a problem with a "layered specifications" approach
that defined a link architecture in a separate document that might or might
not be required.

 Paul prescod
Received on Wednesday, 22 January 1997 21:45:25 UTC

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