> From [log in to unmask] Tue Apr 1 17:12 MET 2003
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> Date: Tue, 1 Apr 2003 09:12:02 -0600
> From: "Thomas G. Habing" <[log in to unmask]>
> Subject: Re: Really old dates vs. W3CDTF/ISO 8601
>
> Douglas Campbell wrote:
> > Roland,
> >
> >
> >>>>[log in to unmask] 31/03/03 21:30:52 >>>
> >>>
> >>>Therefore, does anyone have suggestions/experience in encoding old dates?
> >>
> >>Have you tried xml-schema-part2 date and time datatypes?
> >
> >
> > Ah hah! You can tell I haven't delved deep enough into XML Schemas yet...
> >
> > XSD certainly does offer negative years plus unlimited digits in the year, however it appears I need to select the particular datatype depending on the granularity of each date (unlike ISO8601/W3CDTF where one size fits all), ie.
> >
> > http://www.w3.org/2001/XMLSchema-datatypes#date for -0800-01-01
> > http://www.w3.org/2001/XMLSchema-datatypes#gYearMonth for -0800-01
> > http://www.w3.org/2001/XMLSchema-datatypes#gYear for -0800
>
> If you were using XML Schemas you could do something like this:
>
> <xs:simpleType name="W3CDTF">
> <xs:union memberTypes="xs:gYear xs:gYearMonth xs:date xs:dateTime"/>
> </xs:simpleType>
>
> creating a custom datatype which is a union of the different XML Schema date
> types which would allow the various different granularities of dates to be
> used interchangeably. We've done this for various of the XML Schema we have
> developed for DC.
>
> Not sure how this might work in relation to what is happening with the RDF
> datatyping work, however.
Thanks Thomas for bringing this up -
There is still some kind of gap between XML Schema simple datatyping and
RDF datatyping by means of how a URI should be assigned to USER defined datatypes
and how (fundamental) facets formally might influence reasoning.
With respect to W3CDTF as a W3C Note it is, that i don't like it anymore at all.
Using the individual built in date/time datatypes of XML-schema does not pose such a
problem:
The XML-schema-part2 specification ex-cathedra assigns the URI
http://www.w3.org/2001/XMLSchema#gYear to xsd:gYear
so
<dcq:temporal rdf:datatype="&xsd;#gYear">-0200</dcq:temporal>
works (with new xsd-datatypes aware RDF parsers).
Cheers,
rs
>
> --
> Thomas Habing
> Research Programmer, Digital Library Projects
> University of Illinois at Urbana-Champaign
>
>
> >
> > It also means I might have multiple encoding schemes for dates in my data, eg for a modern painting of old stuff:
> > <rdf:Description>
> > <dcq:created>
> > <dcq:W3CDTF>
> > <rdf:value>1950</rdf:value>
> > </dcq:W3CDTF>
> > </dcq:created>
> > <dcq:temporal>
> > <xsd:gYear>
> > <rdf:value>-0200</rdf:value>
> > </xsd:gYear>
> > </dcq:temporal>
> > </rdf:Description>
> >
> > The nicest way (for me) would be if W3CDTF happened to cater for the ISO 8601:2000 extensions...
> >
> > Thanx,
> > Douglas
> >
> >
>
>
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