John & Co.
It is good to read that DwC would now be finalised as a TDWG standard. When we are promoting biodiversity data sharing, it helps to convince new followers when we can unambigously state that we are using real agreed standards.
My comments to some of the points
- Is species occurrence in nature and in collections the right scope
for the Core?
Occurrence of an organism in nature is the core of the core.
Collection specimens is already a step more specialised, and those elements could go to an specimen extension or curatorial extension.
This is more or less already taken care and what is left is mainly matter of language. I always have trouble explaining to field observers that they need to use Collector for Observer or Reporter. It is confusing to speak of Collector when no specimen was collected. Same with CollectionCode which really is something like CatalogCode or DatasetName.
- Should the general philosophy of the Core be inclusive or
minimalist? What are the characteristics of a concept that allow it to be in the Core? What are the characteristics of a concept that allow it to be added to an existing extension?
Minimalist core but inclusive extensions.
- What are the defining characteristics of a group of related
concepts that justify the creation of a new extension? Should extensions be based on abstract conceptual groupings/objects (events, identifications/determinations, places)? Or on special interests (paleo, curation, interaction)? Or on the stability of the concepts (core contains the proven stable concepts, extensions are more volatile)?
I favour an approach where the extensions are created by communities of users, such as invasive species, agriculture, forestry, observers, botanic gardens, museum collections, etc. Each of these groups already have their own databases where the necessary elements can be found.
- Should there be elements in the Core and extensions to hold GUIDs
linking them to instances of related classes of objects, such as an occurrence to a TaxonConceptGUID, or an occurrence to a CoreGatheringGUID? Should every extension have a non-mandatory GUID allowing for the external resolution of the object?
The core now has GlobalUniqueIdentifier, which can be used to resolve to the other identifiers for gathering, taxon etc. But that is tricky, and I doubt how many people can really deal with it. I would probably want to add direct GUIDs for those most important linking elements, but package them all into a Linking Extension. In particular we should include GUID for the taxonomic concept. That is because LSIDs are now available from SP2000, and probably from some others as well. Lets start using them!
The above also concerns the References Elements that need to be removed from the core, IMHO.*.. *
- Is it the right approach to have restrictions on content at the
concept definition level?
Only in cases when the restriction stems from mathematical or logical rule, then restrict. For agreed sets of values I would refer to community practice. Communities need to keep such lists, which can dynamically be changed as agreed, and without need to update standard versions.
Regards, Hannu