Re: Review of XML Schema Datatypes in RDF and OWL

Hi Ashok

just to let you know that this comment missed the freeze date before 
first publication (still in progress). Thus we will handle this as the 
first comment against the public working draft.

I am sorry that I seem to have made a number of technical errors 
misrepresenting the work of the XQuery and XSLT WGs and these will be 
corrected in due course.

A further detailed reply will be forthcoming sometime after our first 
draft is published. I am looking at a very busy May, so it may not be 
until mid-June. (I think the majority of your comments refer to parts of 
the draft for which I am the lead editor)

thanks

Jeremy


Ashok Malhotra wrote:
> Resending with subject line and improved formatting.
> 
> All the best, Ashok
>  
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>>-----Original Message-----
>>From: w3c-xsl-query-request@w3.org 
>>[mailto:w3c-xsl-query-request@w3.org] On Behalf Of Ashok Malhotra
>>Sent: Monday, April 11, 2005 4:12 PM
>>To: public-swbp-wg@w3.org
>>Cc: w3c-xsl-query@w3.org
>>Subject: [w3c-xsl-query] <none>
>>
>>The W3C XQuery and XSLT WGs asked me to review the document 
>>entitled XML Schema Datatypes in RDF and OWL.  The review 
>>attached below has been approved by the WGs.  
>>All the best, Ashok
> 
> 
>>Review of XML Schema Datatypes in RDF and OWL (Editors' Draft 
>>2005/01/27)
>>
>>The RDF and OWL Recommendations use the simple types from XML 
>>Schema and some of the operators from the F&O document. The 
>>document we reviewed discusses three questions related to this usage: 
>>
>>- What URIref should be used to refer to a user defined datatype? 
>>
>>- Which values of which XML Schema simple types are the same? 
>>
>>- How to use the problematic xsd:duration in RDF and OWL?
>>
>>The document does not attempt to answer these questions in a 
>>definitive manner but, rather, discusses the pros and cons of 
>>different approaches.  
>>
>>Section 1.3
>>
>>This section refers to "derivation by list" and "derivation 
>>by union".  This is, indeed, the XML Schema 1.0 usage but it 
>>has caused widespread misunderstanding as the derived types 
>>are not subtypes of the types they were derived from.  This 
>>usage is being changed in XML Schema 1.1 to "constructed by 
>>list" and "constructed by union".
>>
>>How to Refer to User-defined Datatypes
>>
>>Two approaches are discussed:  use the name of the derived 
>>typed as a fragment identifier with the Schema target 
>>namespace and the SCD approach recommended by XML Schema.
>>
>>Although it is not our place to make a recommendation here, a 
>>couple of points need to be made.  The first approach speaks 
>>about the using the URI "of the document".  This usage will 
>>cause some members of the Schema WG extreme distress as they 
>>take the position that Schemas are not isomorphic to 
>>documents.  Thus, "schema target namespace" is recommended.
>>
>>The use of fragment identifiers is non-standard.  Although 
>>others use fragment identifiers in non-standard ways the use 
>>needs to be clearly delineated.
>>
>>The SCDs approach is the approach favored by the XML Schema 
>>WG and, although the fragment identifier approach is simpler, 
>>please look at the latest SCD draft from XML Schema.  It is 
>>possible that they may be willing to enter into a dialog and 
>>make changes to the SCD draft to accommodate your needs better. 
>>
>>3 Comparison of Values
>>
>>There is an extended disquisition on equivalence of values.  
>>Not much new here.  But please look at the newly introduced 
>>promotion scheme from xs:anyURI to xs:string.  Please also 
>>note that xs:hexBinary can be cast to xs:base64Binary and 
>>that comparisons on values of these two types can be made 
>>after casting. 
>>
>>3.5 eq
>>
>>The document says that 'eq' returns 'true' or 'false' or that 
>>the values are not comparable.  This is not the case.  The 
>>'eq' operator returns a type error if the values are 
>>incomparable and returns the empty sequence if one or both 
>>operands is the empty sequence.
>>
>>The final example is incorrect "INF"^^xsd:float eq 
>>"INF"^^xsd:float does return 'true'.
>>
>>Please use the F&O functions to test for equality.
>>
>>4. Duration
>>
>>The document discourages the use of xs:duration and instead 
>>recommends the use of xdt:dayTimeDuration and 
>>xdt:yearMonthDuration.  We agree.
>>.
>>
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Received on Tuesday, 26 April 2005 14:34:45 UTC