[tdwg-content] Occurrences, Organisms, and CollectionObjects: a review

Steve Baskauf steve.baskauf at vanderbilt.edu
Thu Sep 8 13:02:49 CEST 2011

comments inline

John Wieczorek wrote:
> I am fine with the idea that the CollectionObject can be evidence for
> anything, I may have been projecting or misinterpreting what others
> said. Can you recommend a better definition than the one I provided?
I don't think that the definition of CollectionObject which you gave 
needs to be changed.  Being derived from an Organism is the minimal 
requirement for a collection object.  If it can do other things (be 
evidence for an Occurrence, support an Identification, or anything else) 
that's great but not required.  If it has a collection date, location of 
collection, or both, which CollectionObjects usually do, then it would 
be evidence for an Occurrence as well as evidence that the organism existed.

Richard Pyle wrote:
> One concern I do have, however, is in the many, many, many cases where there
> will be a 1:1 relationship between an Organism and a CollectionObject (i.e.,
> the vast majority of all Museum specimens).  Does that mean that data
> providers will need to generate two separate Ids (one organismID and one
> collectionObjectID) to represent all of these specimens?
Shockingly, I think I agree with everything Rich wrote in response to 
Gregor's email.  As far as this question is concerned, I would say that 
whether one generates a single ID or two IDs is up to the user.  
Assuming that one has GUIDs of some form (LSID, HTTP URI, or whatever), 
then if one wishes to consider the dead fish in the jar both the 
Organism and the CollectionObject, then use a single GUID for both 
organismID and collectionObjectID.  If one prefers to think of the fish 
as a Platonic ideal of Organism in all of its incarnations (living and 
dead) but the fish in a jar as the CollectionObject, then give them 
separate GUIDs.  That really is a data management decision by the GUID 
creator.  I was hung up on this issue for a very long time, but after 
mulling it over I realized that I was only hung up about it because I 
assumed that all classes in DwC had to be disjoint (sensu OWL).  They 
almost always are, but in this case I don't see any reason why they 
would have to be.  DwC simply uses classes to categorize things and to 
suggest the types of terms that one might use to describe instances of 
those classes, but otherwise stays out of our personal data management 

Richard Pyle wrote:
> I think I might agree with this, but I want to ask a simple question:
> To what objects would an Identification instance apply?  In other words, an
> Identification instance represents a link between an instance of Taxon to an
> instance of [XXXXXXX].
> In my mind, this should always be "Organism".  To me, neither an Occurrence
Totally.  Is this the first time I've agreed with everything Rich has 
said?  :-)

Steven J. Baskauf, Ph.D., Senior Lecturer
Vanderbilt University Dept. of Biological Sciences

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