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[RESPONSE qt-2004Feb0384-01] [General] Please use less namespaces

From: Jonathan Robie <jonathan.robie@datadirect.com>
Date: Wed, 10 Nov 2004 18:24:08 -0500
Message-ID: <4192A318.5060605@datadirect.com>
To: Martin Duerst <duerst@w3.org>
CC: public-qt-comments@w3.org, w3c-i18n-wg@w3.org

Martin Duerst wrote:

> The less namespaces, the easier to use. For example,
> I don't see any need to have the xdt namespace; these
> few types, if they are needed, should be added to XML
> Schema, and to that namespace.

Hi Martin,

We agree that namespaces should not be introduced gratuitously, but only 
as needed. You raise one example, the xdt namespace, asking us to 
eliminate it or move it to XML Schema.

The xdt namespace contains three types not found in XML Schema: 
xdt:dayTimeDuration, xdt:yearMonthDuration, and xdt:untypedAtomic. The 
first two may or may not eventually find their way into XML Schema, but 
the third will not.

The reason is that XQuery must distinguish xdt:untypedAtomic, a type 
that has no subtypes and actively asserts that data is not declared to 
have a type, from xs:anySimpleType, which is the base type for all 
simple W3C XML Schema data types. W3C Schema does not have a type that 
is used to declare that an item was not declared using a type. 
Therefore, XQuery and XPath map untyped data to this type. Note that 
even if this type were added to XML Schema, which is unlikely, we would 
still encounter untyped data in XML that is not validated using a W3C 
XML Schema, e.g. merely-well-formed XML, DTD-validated XML, 
RNG-validated XML, etc. Eliminating xdt:untypedAtomic would be a deep 
change in our type system, requiring radical restructuring of XQuery and 
XPath 2.0.

We have decided to close this issue with no change to our documents. 
Please let us know if this is unacceptable to the I18N Working Group.

Thanks!

Jonathan
On behalf of the W3C XML Query and XSLT Working Groups
Received on Wednesday, 10 November 2004 23:24:38 UTC

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