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Re: RDF C14N Inclusive or Exclusive

From: Joseph Reagle <reagle@w3.org>
Date: Mon, 4 Mar 2002 10:26:36 -0500
Message-Id: <200203041526.KAA15866@tux.w3.org>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>, <w3c-rdfcore-wg@w3.org>, <w3c-ietf-xmldsig@w3.org>
On Monday 04 March 2002 09:45, Jeremy Carroll wrote:
> Under exclusive C14N the literal value is:
> "\n    <foo xmlns=""
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
> xsi:type="xsd:decimal">10.09</foo>\n  "
>
> because only the xsi and default namespaces are visibly used.
>
> I note that in some sense the exclusive C14N has got this example wrong,
> since we need to preserve the binding of the xsd prefix to preserve the
> semantics of this example.

Hrmm... this is interesting. This is the second of two issues (potential 
bugs) that have been raised this week that we need to give serious thought 
to.
1. In your email: should we emit a namespace for prefixes found in an 
attribute value (or even element content?!).
2. If you canonicalize only an attribute (or attribute group) should their 
related namespace declarations also be emitted [1]?


[1] 
http://lists.w3.org/Archives/Public/w3c-ietf-xmldsig/2002JanMar/0152.html
I  haven't played with it in implementations myself. Your use cases 
anticipate this usage? Is my following understanding correct?

<foo:list foo:xmlns="http://example.org/foo">
  <foo:item foo:price="5"/>
</foo:list>

And you want to canonicalize the price attribute? And the result you want 
is akin to (avoiding your prefix rewriting for the moment):

  'foo:price="5" foo:xmlns="http://example.org/foo"' 

whereas Canonical XML yields:

 'foo:price="5"'
Received on Monday, 4 March 2002 10:27:38 EST

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