[tdwg-content] Conflict between DarwinCore and DublinCore usage of dcterms:type / basisOfRecord

[Gregor Hagedorn]

Dear John

we (Gregor Hagedorn, Bob Morris, Steve Baskauf) realize that the
public review period for DarwinCore (DwC) is over, but we believe we
need to bring a potentially highly problematic issue to your
attention. This issue has been found originally by Steve Baskauf.
Essentially, it is an issue that is not very appearant when reading
DarwinCore for review, but detected when trying to implement it in
combination with other technologies.

Steve describes the problem on:
  http://www.keytonature.eu/wiki/MRTGv08_Type_term_inconsistent_with_DwC

DarwinCore seems to use dcterms:type in a way that is inconsistent
with the DublinCore (DC) recommendations for publication artifacts,
which is the way most users of DC are likely to use dcterms:type.
Steve pointed out that MRTG's use, which does follow the DC
recommendation, is inconsistent with DwC. We believe that this is not
a problem of MRTG; the problem equally occurs, e. g., where natural
history collections collaborate with the culture and library initative
Europeana.eu, which equally uses DublinCore type in the original
sense.

DublinCore dcterms:type has an explicit type vocabulary:
  http://dublincore.org/documents/dcmi-terms/#terms-type
whose annotations says: "Recommended best practice is to use a
controlled vocabulary such as the DCMI Type Vocabulary [DCMITYPE]."
This vocabulary:
  http://dublincore.org/documents/dcmi-type-vocabulary/
defines values like StillImage, Sound, MovingImage, Text.

In contrast, the DwC type vocabulary acts on an abstract level of
recording occurrences that are independent of physical records. These
occurrences can then be vouchered by physical resources like
specimens, photos, movies, etc. The actual resources treated in
DublinCore are therefore only potential vouchers for a DarwinCore
resource. The terms recommended for DublinCore "type" are therefore
expected in the DarwinCore "basisOfRecord" property.

We do not mean to imply that there is anything wrong with the
DarwinCore perspective. Unfortunately, we believe that DarwinCore
cannot coexist with DublinCore data, as long as DarwinCode does not
define its own dwc:type/dwc:abstractType property.

-------------

Test case: An image showing a taxon observation shall be documented
both in DarwinCore and DublinCore.

DarwinCore prescribes or recommends dcterms:type=Occurrence, plus:
basisOfRecord:StillImage.

DublinCore recommends dcterms:type=StillImage.

-------------

We have internally begun to discuss possible solutions. In DublinCore,
dcterms:type does not express a particular type of metadata record,
but is metadata about the underlying resource. We therefore consider
replacing the DwC use of dcterms:type with something in the dwc
namespace, and replacing dwc:basisOfRecord with dcterms:type as an
option that minimizes the necessary design changes in DwC. We can see
some other issues arise that depend on how one tries to bring DwC into
closer coherence with the DublinCore recommendations, but perhaps
these are best put forth on a wiki.

Here we would like only to point out that we believe that the values
for basisOfRecord fit into the dcterm:type vocabulary. Observations
(dwc:HumanObservation and dwc:MachineObservation) may be placed as
subtypes of http://purl.org/dc/dcmitype/Event. and specimens
(dwc:PreservedSpecimen, dwc:FossilSpecimen, dwc:LivingSpecimen) as
subtypes of http://purl.org/dc/dcmitype/PhysicalObject. For different
communities, the dwc specimen types may have to be further subtyped as
"Seed", "TissueSample", "DNA_Sample".

However, we believe it is not possible to create a hierarchy like
  "StillImage - isSubtypeOf - Image - isSubtypeOf - Occurrence"
because this is a use-case dependent view: A character image may be a
subtype of a taxon representation, and it may or may not be a subtype
of an occurrence representation.

-------------

Best wishes

Gregor, Bob, Steve

-- 
---------------------------------
Dr. Gregor Hagedorn
Heinrich-Seidel-Str. 2
12167 Berlin
skype: g.hagedorn

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