[tdwg-content] date elements in Darwin Core XML schemas

Bob Morris morris.bob at gmail.com
Wed Jul 20 16:05:53 CEST 2011

I've added this comment to the incident in guarded support of the "correction".

From:  <darwincore at googlecode.com>
> Date: Tue, Jul 19, 2011 at 6:51 PM
> Subject: [dwc-notify:2] Re: Issue 118 in darwincore: eventDate
> validation To: darwincore-notify at googlegroups.com
> Comment #4 on issue 118 by morris.... at gmail.com: eventDate validation
> http://code.google.com/p/darwincore/issues/detail?id=118
> I concur with the clarification, but raise two possible issues that
> may need some best practices offered.
> 1. Possibly ISO 8601:2004 should be specified, or its applicability
> addressed
> 2. If there is a need to reconcile RDF data with XML-Schema-based
> data, then there are some issues to consider.  (a)RDF itself has no
> specification for dateTime (b)SPARQL only(?) supports xsd:dateTime.
> http://www.w3.org/TR/rdf-sparql-query/#operandDataTypes

On Tue, Jul 19, 2011 at 7:03 PM, John Wieczorek <tuco at berkeley.edu> wrote:
> Geoffrey Allen has asked for a clarification about the date fields in
> Darwin Core. Commentary about the problem is recorded in Issue 118
> (http://code.google.com/p/darwincore/issues/detail?id=118) in the
> Darwin Core Issue Tracker. Below is an excerpt of my explanation. The
> bottom line for this mailing list is that I believe Geoffrey has
> revealed an error in the XML Schema
> http://darwincore.googlecode.com/svn/trunk/xsd/tdwg_dwcterms.xsd that
> should be amended. I'm posting it here for commentary to see if there
> is/was any good reason for restricting the dateTime elements in Darwin
> Core more than in the recommendation in the definition of the terms.
> If not, this is a proposal to change the types in that schema from
> xs:dateTime to dateTimeISO.
> Commentary from Issue 118 follows:
> Through the date terms (eventDate, dateIdentified,
> relationshipEstablishedDate, measurementDeterminedDate,
> dcterms:modified) in the Darwin Core recommend the ISO 8601 standard
> for dates, the XML application schema published at
> http://darwincore.googlecode.com/svn/trunk/xsd/tdwg_dwcterms.xsd
> implements the more restrictive xs:dateTime type for these terms. For
> example,
> <xs:element name="eventDate" type="xs:dateTime"
> substitutionGroup="dwc:anyEventTerm"/>
> I'm not sure what the rationale was for implementing these terms as
> xs:dateTime rather than the less restrictive type dateTimeISO (see
> below) defined in
> http://darwincore.googlecode.com/svn/trunk/xsd/tdwg_basetypes.xsd,
> especially since
> http://darwincore.googlecode.com/svn/trunk/xsd/tdwg_dwcterms.xsd
> imports that bastypes schema and has a comment specifically about the
> use of dateTimeISO, which it doesn't actually use. I believe this is
> an unintentional error in tdge_dwcterms.xsd, but will post this to the
> tdwg_content list to see if there is any dissenting opinion about
> "correcting" it.
> <xs:simpleType name="dateTimeISO">
> <xs:annotation>
> <xs:documentation xml:lang="en">
> The date and time expressed in a way conforming to a subset of ISO
> 8601. Meant to be exactly the same as DateTimeISO defined in ABCD.
> </xs:documentation>
> </xs:annotation>
> <xs:restriction base="xs:string">
> <xs:pattern value="\d\d\d\d(\-(0[1-9]|1[012])(\-((0[1-9])|1\d|2\d|3[01])(T(0\d|1\d|2[0-3])(:[0-5]\d){0,2})?)?)?|\-\-(0[1-9]|1[012])(\-(0[1-9]|1\d|2\d|3[01]))?|\-\-\-(0[1-9]|1\d|2\d|3[01])"></xs:pattern>
> </xs:restriction>
> </xs:simpleType>
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Robert A. Morris

Emeritus Professor  of Computer Science
100 Morrissey Blvd
Boston, MA 02125-3390
IT Staff
Filtered Push Project
Department of Organismal and Evolutionary Biology
Harvard University

email: morris.bob at gmail.com
web: http://efg.cs.umb.edu/
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phone (+1) 857 222 7992 (mobile)

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