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RE: two failings of XLink

From: Didier PH Martin <martind@netfolder.com>
Date: Fri, 27 Sep 2002 10:17:56 -0400
To: "'Micah Dubinko'" <MDubinko@cardiff.com>, <www-tag@w3.org>
Cc: <elharo@metalab.unc.edu>
Message-ID: <000001c26630$ad987b70$c801a8c0@didierhome>

Hi Micah

Eliot proposed:
<object xmlns:xlink="http://www.w3.org/TR/1999/xlink">
   <longdesc xlink:href="http://www.example.com"/>
   <src xlink:href="http://www.example.org"/>
   <someotherlink xlink:href="http://www.example.net"/>
   Look Mom! We can put alternate text here!
   We can even <strong>markup</strong> the alternate text.
   Hell, we can even provide a classic HTML
   <img src="http://www.example.org"/> for browsers that don't support
   XHTML2. I learned this trick from Java.
</object>

Micah responded:
Elimination 3: Extended XLink. If the DTD provided an
xlink:type="extended"
attribute on <object>, as well as xlink:type="locator" attributes on the
first three child elements, this could be considered an Extended XLink.

But what is it linking? Well, there are three participating endpoints,
all
remote. So once again, the <object> element is not, in XLink 1.0 terms,
part
of the link. Further, due to the absence of xlink:type="arc" elements,
default arcing kicks in and there are a total of six arcs present: to
and
from every endpoint. That's a great feature for linkbases, but
unfortunately
not what we were trying to do.

Didier replies:
Good, we are starting to use the gray matter area now :-). At least we
are now we dissecting the beast and exploring the possibilities. Let's
keep the third hypothesis that can bring more benefit than the others
Hypo. = If the object element is an extended link.

The main problem seems to be the arc role definition. If I understand
well your interpretation(1), the document - containing an object element
that itself derives from an xlink extended link - needs to include also
an arc element to specify the arc direction. Said differently, the
presence of an xlink extended element is not a sufficient and necessary
condition to make it an extended link. To make it so, it needs an arc
element to provide that additional information. Is this what you say?

(1) which may be right, I just need some time to read and read again the
spec section 5.1 to grasp all the subtle details and the possible
residual potential bugs contained in it

Cheers
Didier PH Martin 
Received on Friday, 27 September 2002 10:18:16 GMT

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