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LC-217 pattern facets on complex types

From: C. M. Sperberg-McQueen <cmsmcq@acm.org>
Date: Fri, 06 Oct 2000 00:04:45 -0600
Message-Id: <>
To: "Martin J. Duerst" <duerst@w3.org>, Misha Wolf <misha.wolf@reuters.com>
Cc: W3C XML Schema Comments list <www-xml-schema-comments@w3.org>
Dear Misha and Martin:

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).

Among other issues, you raised the point registered as issue LC-217,
which suggests that XML Schema be modified to allow the 'pattern'
facet of simple type definitions in the definition of complex types
as well.

We thank you for the comment, but we have not found ourselves
willing to make the suggested change to XML Schema.

Some members of the WG felt that your comment suggests you have
mistaken the nature of mixed content, and have taken it for data with
some simple datatype (e.g. String). Mixed content does not map,
however, to any simple type. If it is ever reasonable to restrict data
to a particular character repertoire, either this is a general problem
of supporting a restricted character set in some system or locale, or
else it is a problem specific to particular fields.

In the latter case, the fields can and should be typed, and the types
can be restricted as described in the responses to last-call issue

In the former case, the functionality is required (as we understand
it) in order to support legacy systems which cannot handle Unicode. In
this case, it seems to us that out-of-band measures are preferable.
There is serious resistance in the WG to doing anything which could be
taken as encouraging the development or continued use of systems which
cannot support the full range of UCS-4 characters: we believe you will
agree that widespread support for Unicode and ISO 10646 are an
important step toward better solutions to i18n and l10n problems.

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 Thursday, 5 October 2000 21:49:59 UTC

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