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C14n and XML declaration?

From: Joseph M. Reagle Jr. <reagle@w3.org>
Date: Wed, 23 Jun 1999 14:29:45 -0400
Message-Id: <>
To: www-xml-infoset-comments@w3.org
Cc: "IETF/W3C XML-DSig WG" <w3c-ietf-xmldsig@w3.org>, "XML Syntax WG" <w3c-xml-syntax-wg@w3.org>
The XML Syntax WG has discussed whether the XML resulting from C14N should
include an XML declaration describing the version of the XML generated by
the C14N processor.  [1] This discussion has happened in the context that
the we do not even consider the original content's declaration since it is
only an optional property of the Infoset -- and we decided the C14N XML will
be a syntactical representation of a subset of the required Infoset. 

Consequently, what led to the decision of making that information optional?
It is possible that the digital signature community will find this
contextual information critical to the meaning of the document. (As an
optional item, two documents which are similar aside from the declaration
will be appear to be the same.) 


Message-Id: <>
Date: Thu, 17 Jun 1999 09:47:13 -0700
To: "XML Syntax WG" <w3c-xml-syntax-wg@w3.org>
From: Tim Bray <tbray@textuality.com>
Subject: C14n issue N4 - XML declaration?

Should the canonical form include the XML declaration?  Subsidiary
question: if so, which of the encoding and standalone declarations
should it include?

Let's hear opinions and nail this down next Wednesday.

Minor pro:
 XML docs with XML declarations are more robustly interchanged
Minor con:
 A couple of dozen extra bytes

Serious issue: if we include the XML declaration, that makes the
version of XML part of the canonical form. The corollory is that
should there ever be an XML 1.1 or 2.0, no XML 1.1/2.0 document
can ever be canonically equivalent to any XML 1.0 document.  Is
this a good or bad thing?   

Note: if we leave the XML Decl out, and specify that this C14n
spec applies *only* to XML 1.0 documents, we can postpone the
decision about whether XML1 and XML2 docs can ever be canonically
equivalent to the time we write the XML2 c14n spec.  Sounds good
to me. -Tim

Joseph Reagle Jr.   
Policy Analyst           mailto:reagle@w3.org
XML-Signature Co-Chair   http://w3.org/People/Reagle/
Received on Wednesday, 23 June 1999 14:29:48 UTC

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