[tdwg-tag] "Class" attribute in DwC

Richard Pyle deepreef at bishopmuseum.org
Sat Aug 8 19:21:55 CEST 2015

It sounds like perhaps now is the time to focus on the ontological
relationships among classes, as the next major focus of DwC advancement. 

I would NOT regard "HumanObservaton" as a subclass of "Event".  I believe
that "Event" should be kept clean as fundamentally an intersection between a
Location instance and a point in time.  After much thinking and testing on
this, we've finally come to the conclusion in our data models that
"Location" is defined by two of the four space-time dimensions (X & Y;
effectively represented as Geocoordinates -- whether as a point,
Point/radius, track, polygon, etc.), and "Event" is defined by one Location
instance plus the other two space-time dimensions (Z & T; effectively
represented as elevation, depth and date/time).  I'd be happy to explain why
we came to this conclusion, but that's another thread.

The point is that I think "Event" should remain as an abstract
four-dimensional address, created as an instance to capture space-time
information for something else.  In DwC, that "something else" is an

Within the confines of existing DwC, "HumanObservation" comkes closes to
being a subclass of Occurrence.  However, there is still one missing class
that I believe we need to complete the core ontology space of DwC -- which
is what we refer to as "Evidence", and Darwin-SW refers to as "Token"
(https://code.google.com/p/darwin-sw/).  Our model draws the lines slightly
differently from the diagram for D-SW, but in general they represent a
convergence of thinking on the relationships among DwC classes.

In answer to Steve's question:

> dwc:HumanObservation rdfs:subClassOf dwc:[Occurrence]
> But what would I gain by doing that?  What would it prevent me from doing?

I'm not technically savvy enough to answer that question from an
implementation perspective; but from a DwC comprehension perspective, it
moves us a step closer to mutual understanding of how to transform DwC
content into a functional data model.  We all kinda/sorta know that already,
but as evidenced by the different perspectives of "HumanObservation as a
subclass of Event" vs. "HumanObservation as a subclass of Occurrence" just
now revealed & expressed, it probably wouldn't hurt to be more explicit
about these sorts of things in DwC documentation.

> -----Original Message-----
> From: tdwg-tag-bounces at lists.tdwg.org [mailto:tdwg-tag-
> bounces at lists.tdwg.org] On Behalf Of Steve Baskauf
> Sent: Saturday, August 08, 2015 2:47 AM
> To: Bob Morris
> Cc: tdwg-tag at tdwg.org
> Subject: Re: [tdwg-tag] "Class" attribute in DwC
> I think that this has been left intentionally vague because at this point
we don't
> have well-defined relationships among Darwin Core classes.  It seems to me
> that placing the class terms on the same line are a clue that they are
> related, but it isn't apparent to me that the subsequent terms are always
> special cases of the left-most terms.  I can provide an example where a
> LivingSpecimen isn't a MaterialSample because it was never collected.  I
> also imagine Event instances which include many HumanObservations (i.e.
> Event serves to group observations, not to serve as a superclass for
> observations).
> There have been various attempts to lay out how the Darwin Core classes
> related to each other.  But I'm not aware that there has ever been a
> on it.  That's why the RDF Guide didn't touch the issue.  We were afraid
that the
> guide would never be finished if we took up that subject.
> I think it would be an excellent exercise to try to lay out how Darwin
> classes are related to each other.  But first, I would suggest that we lay
out the
> use cases that we intend to satisfy by nailing down those relationships,
> show how establishing those relationships help us.
> For example, I could suggest that we establish that
> dwc:HumanObservation rdfs:subClassOf dwc:Event.
> But what would I gain by doing that?  What would it prevent me from doing?
> Steve
> Bob Morris wrote:
> > The current DwC Terms [1]   (carrying Identifier
> > http://rs.tdwg.org/dwc/2015-03-19/terms/ and Date Modified: 2015-06-02
> > ) is confusing  (confused? silent? ) about the relation of the "sister
> > classes" to the terms intended (?) to be used therewith.  For example,
> > dwc:Event, dwc:MachineObservation, and dwc:HumanObservation could
> > reasonably(?) all have dwc:eventDate applied to them. But
> > http://rs.tdwg.org/dwc/terms/index.htm#eventDatesuggests
> > Class=dwc:Event.
> >
> > Now it's human-clear that for each of the "multiple" boldface lines in
> > the index, the second and subsequent terms are meant to be special
> > cases of the left most one. What I can't see is whether [1] intends to
> > encourage (require?) this in some explicit way, and where that
> > explicit way is to be found.  (I had a dream that the DwC RDF Guide
> > might take a position....) .
> >
> > Thanks.
> >
> > --Bob
> > p.s. I concede that some answers might lurk in the ongoing move of
> > resources to http://tdwg.github.io/dwc/terms/.  My second dream was
> > that tdwg.github.io does Content Negotiation and curl would rescue
> > me....
> >
> > [1] http://rs.tdwg.org/dwc/terms/index.htm
> >
> >
> --
> Steven J. Baskauf, Ph.D., Senior Lecturer Vanderbilt University Dept. of
> Biological Sciences
> postal mail address:
> PMB 351634
> Nashville, TN  37235-1634,  U.S.A.
> delivery address:
> 2125 Stevenson Center
> 1161 21st Ave., S.
> Nashville, TN 37235
> office: 2128 Stevenson Center
> phone: (615) 343-4582,  fax: (615) 322-4942 If you fax, please phone or
> so that I will know to look for it.
> http://bioimages.vanderbilt.edu
> http://vanderbilt.edu/trees
> _______________________________________________
> tdwg-tag mailing list
> tdwg-tag at lists.tdwg.org
> http://lists.tdwg.org/mailman/listinfo/tdwg-tag

More information about the tdwg-tag mailing list