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Arbortext dissent on OASIS request to allow locating schemas via public ids

From: Paul Grosso <pgrosso@arbortext.com>
Date: Thu, 15 Feb 2001 16:33:02 -0600
Message-Id: <>
To: w3c-xml-schema-wg@w3.org
Arbortext would like to register a formal dissent on the issue
regarding the OASIS request to allow locating schemas via public
ids [1] (there was no CR number).

Though the conversation was often side-tracked by other issues,
I find the key points to be as follows.

The XML Recommendation defines an "external identifier" (ExternalID,
production 75 [2]) that identifies external entities.  The external
identifier is composed of two identifying strings:  one, called the
system identifier, that is a required part of the external identifier,
and another, called the public identifier, that is optional.

Document instances need to be able to reference external entities
including the various schemas against which that instance should
validate.  The current XML Schema specification provides the
xsi:schemaLocation attribute to allow the instance to give the
system identifier part of a schema's external identifier, but
there is no way for the user to provide the public identifier
part of a schema's external identifier within the document
instance.  Since instances can provide both the public and
system identifier of its external declaration subset (aka DTD),
this missing capability for schemas seems to short-change both
the XML 1.0 spec and the Schema design goal to provide for similar
needs as those address by DTDs.

All it would take to support this user need would be to add, say,
an xsi:schemaPublicId attribute which, analogously to schemaLocation,
would pair namespace names with public ids.  The decision not to do
this leaves schema users unable to take advantage of what some people
see as an integral part of XML external entity processing.


[1] http://lists.w3.org/Archives/Public/www-xml-schema-comments/2001JanMar/0149
[2] http://www.w3.org/TR/REC-xml#NT-ExternalID
Received on Thursday, 15 February 2001 17:33:25 UTC

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