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Re: XML Canonicalization Requirements

From: <MARUYAMA@jp.ibm.com>
Date: Thu, 1 Apr 1999 07:04:28 +0900
To: "Joseph M. Reagle Jr." <reagle@MIT.EDU>
cc: "Signed-XML Workshop" <w3c-xml-sig-ws@w3.org>
Message-ID: <4925674A.00445940.00@d22mta10.yamato.ibm.com>


>  - the XML-namespace draft allows changes in prefixes that
>    applications are supposed to ignore. I think DOM-HASH and other
> processors
>    will have to expand the namespace of every single ns-identifier so as
> ensure they
>    have a non-ambiguis hash, no?

Yes, I think they have to.  DOMHash is defined on the "expanded name"
whenever a name is qualified (either by default or an explicit namespace

>  - if a document has a DTD and in the DTD there are fixed or default
>    attributes that don't occur in the instance, do we consider those
>    attributes to be part of the instance or not?

I think we want to consider them as a part of canonicalization.
XML 1.0 Recommendation clearly states that if an XML processor encounters
an omitted attribute, it is to behave as though the attribute were
present with the declared default value.  DOMHash assumes that
the DOM structure is created by a conformant XML processor, so
it counts the recovered attributes in the hash calculation.

>  - if a document has a DTD that defines "unparsed entities" (links to
>    images and such; yeah, I know people should use Xlink for that,
>    but XML still allows it) then the internal name of the entity is
>    arbitrary. Should it be renamed in the canonical form?

>  - to what degree should the semantic or surface structure of referenced
>    resources be included in the hash? Where would you come down in
> addressing
>    the old problem (even from PICS days) of what is the semantic scope of
> resource
>    that links or is composed of other resources?

Hiroshi Maruyama
Received on Monday, 5 April 1999 08:24:39 UTC

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