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LC-186 naturalizing names from other namespaces

From: C. M. Sperberg-McQueen <cmsmcq@acm.org>
Date: Mon, 09 Oct 2000 18:37:06 -0600
Message-Id: <>
To: Daniel Veillard <Daniel.Veillard@w3.org>
Cc: W3C XML Schema Comments list <www-xml-schema-comments@w3.org>
Dear Daniel:

The W3C XML Schema Working Group has spent the last several months
working through the comments received from the public on the last-call
draft of the XML Schema specification.  We thank you for the comments
you made on our specification during our last-call comment period, and
want to make sure you know that all comments received during the
last-call comment period have been recorded in our last-call issues
list (http://www.w3.org/2000/05/12-xmlschema-lcissues).

According to our issues management system, you raised the point
registered as issue LC-186, which suggests that some mechanism be
provided for allowing attribute remapping (or, more generally, for
allowing names from other namespaces to be 'naturalized' by being
associated with names in the local namespace).

The WG discussed this topic at some length, and considered several
possible approaches; in the end, the WG decided not to add this
feature to version 1.0, though it may be a good topic to consider for
future versions of XML Schema.

Some members of the WG felt that the underlying problem raised by your
note is the same problem which 'architectural forms' attempt to solve.
(Some also felt that the problem reflects a fundamental design error
in the Namespaces in XML recommendation, but that is not a consensus
view within the WG.)  One possible solution, therefore, which requires
no changes to XML or to XML Schema, is simply to use architectural
forms as they are defined by the relevant ISO standards and
implemented by existing software.

With regard to element types, the substitution-group mechanism of XML
Schema can be used to define equivalences of the kind needed (I define
an element in my namespace as being in the substitution group of an
element in some other namespace).  Some WG members were in favor of
extending the substitution-group mechanism to attributes, but this
seemed to the majority to be a change better left for later versions
of the specification.

In the context of XML Linking, the WG reached the conclusion that in
fact a better solution to the problem is for applications to recognize
XPointers on the basis of their datatype, rather than solely on the
basis of their name.

The upshot is that there appear to be mechanisms already available
(architectures and simple types) to solve the basic problem.  So the
WG decided against adding a new mechanism to the spec in order to
provide yet another method to solve it.

It would be helpful to us to know whether you are satisfied with the
decision taken by the WG on this issue, or wish your dissent from the
WG's decision to be recorded for consideration by the Director of
the W3C.

with best regards,

-C. M. Sperberg-McQueen
  World Wide Web Consortium
  Co-chair, W3C XML Schema WG
Received on Monday, 9 October 2000 14:39:04 UTC

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