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Re: Comments on XML-Link Spec

From: Peter Murray-Rust <Peter@ursus.demon.co.uk>
Date: Tue, 20 May 1997 22:23:34 GMT
Message-Id: <6957@ursus.demon.co.uk>
To: w3c-sgml-wg@w3.org
In message <199705171509.LAA05066@ids2.idsonline.com> "Eric Johnson" writes:
[... a lot of very important questions about link terminology ...]

The more I have been thinking about LINK the more unresolved issues I think
we have, and I would very much like knowledgeable comments about what we
all agree and where we start to differ.  Because I think in concrete terms, 
I would like answers about link terminology, applied to an example.  If
nothing else it would help me get my program right. :-)

Here's the simple example.  I shall omit all ACTUATE and SHOW at this stage.

<!ATTLIST A XML-LINK CDATA #FIXED "SIMPLE">

<CHAPTER>
Once upon a time there was a 
<HOUSE ID="h1">
in which lived
<BEAR TITLE="Father" ID="b1"><BED XML-TYPE="hard"/></BEAR>
<BEAR TITLE="Mother" ID="b2"><BED XML-TYPE="soft"/></BEAR>
and
<BEAR TITLE="Baby" ID="b3"><BED XML-TYPE="OK"/></BEAR>
</HOUSE>.  One day
<GIRL TITLE="Goldilocks"/> came to a
<A HREF="#h1" ROLE="A" TITLE="houseLink">charming little house</A> but the
<A HREF="ROOT,DESCENDANT(ALL,BEAR)" ROLE="B" TITLE="bearsLink">three bears</A>
were not at home.
</CHAPTER>

The semantics of the elements are undefined.  

Firstly I believe there are two independent SIMPLE links, OK?

LINK: ROLE=A:
This link has a TITLE (label) = houseLink
Does this link have one or two resources?  It locates a part of the document
- a HOUSE element, which contains #PCDATA, BEAR (BED), BEAR (BED), #PCDATA and
BEAR (BED).  This is a single resource?
I am not clear whether it has another resource.  If so this is EITHER:
#PCDATA ("a charming little house") OR
an A element containing #PCDATA.  Which?

LINK: ROLE=B:
This link has a title 'bearsLink'
IMO this link locates THREE independent resources, BEAR (b1), BEAR (b2) and
BEAR (b3).  This is not a span, as these could be anywhere in the document.
It is impossible to tell by looking at LINK ROLE=B what the form of the
resource(s) are.  Therefore I would simply say that (ALL,*) locates a
resourceSet and not a resource.


Going through the rest of the terminology, I would call an 'A' element a
*linking element*, the value of the HREF a *locator*, the value of the TITLE
a *label*, the process (*if any) initiated by clicking on 'A' a *traversal*,
the whole A element an *in-line link* and there are no out-of-line links and
no multi-directional links.

The link formatting would be application dependent.  It could:
	paint the content of A blue (as in HTML)
	draw an icon derived from ROLE or TITLE


The question of resources is particularly important and we need urgent 
clarification here.

	P.


-- 
Peter Murray-Rust, domestic net connection
Virtual School of Molecular Sciences
http://www.vsms.nottingham.ac.uk/
Received on Tuesday, 20 May 1997 18:03:55 UTC

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