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RE: Re: Timezones and xsd:dateTime/xsd:date

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Thu, 6 Sep 2007 17:53:36 +0100
Message-ID: <86FE9B2B91ADD04095335314BE6906E801722782@sdcexc04.emea.cpqcorp.net>
To: "Eric Prud'hommeaux" <eric@w3.org>
Cc: "Lee Feigenbaum" <lee@thefigtrees.net>, "RDF Data Access Working Group" <public-rdf-dawg@w3.org>




-------- Original Message --------
> From: Eric Prud'hommeaux <mailto:eric@w3.org>
> Date: 6 September 2007 17:21
> 
> I read this as saying that in *XQuery*
>   "20070906T12:08"^^xsd:dateTime is always >
> "20070906T12:07"^^xsd:dateTime (and "20070906"^^xsd:date is always >
> "20070906"^^xsd:date)  

That is, no timezone info.

(Actually in ARQ "20070906"^^xsd:date = "20070906"^^xsd:date :-)

> 
> [[
> C.2 Dynamic Context Components
> 
> The following table describes how values are assigned to the various
> components of the dynamic context. All these components are initialized
> by mechanisms defined by the host language. For each component,
> "global" indicates that the value of the component remains constant
> throughout evaluation of the XPath expression, whereas "dynamic"
> indicates that the value of the component can be modified by the
> evaluation of subexpressions.      
> 
>                                    Dynamic Context Components
> ‚€€€€€€€€€€€€€€€€€€ˆ€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€ƒ
>       Component                                    Scope       
> †€€€€€€€€€€€€€€€€€€Š€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€‡
> Implicit timezone global; must be initialized by implementation
> „€€€€€€€€€€€€€€€€€€‰€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€… ]]
> --
> http://www.w3.org/TR/2007/REC-xpath20-20070123/#id-xp-evaluation-context-components
> 
> - so, there can be only one implicit timezone for the evaluation of a
> query. 
> 
> I'd like to follow XQuery; will draft clarifying text after lunch.
> 
> Does that influence your interpretation Andy?

I'm following:
http://www.w3.org/TR/xmlschema-2/#dateTime-order

The text you quote does not change my interpretation of the comparison text - it clarifies what happens in XPath/Xquery 

The comparisons both have no timezone so it's case B:

[[
B. If P and Q either both have a time zone or both do not have a time zone, compare P and Q field by field from the year field down to the second field, and return a result as soon as it can be determined.
]]

Cases C and D are the situation where one has a timezone, one does not.

(ARQ uses code from Apache Xerces to actually do the comparison - it can return INDETERMINATE).

	Andy


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Received on Thursday, 6 September 2007 16:54:06 GMT

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