Question to logical structure of DarwinCore classes and properties

[herb52]

Hello,

I am new to DarwinCore (DwC). I want to store DwC-specific data inside photos using the structures and tags (elements of the structure) of xmp-dwc supported by Exiftool. For xmp-dwc please see https://exiftool.org/TagNames/DarwinCore.html

I started with "Darwin Core quick reference guide" on https://dwc.tdwg.org/terms/ Here I see

• classes with properties listed for this classes: e.g.: Record-level with properties: datasetID, collectionCode and many others We have a one-to-one relationship between these .. classes and the ExifTool structures and .. the properties_of_classes to elements/tags_of_structures. Looking on stored data we have always the following structure-tree DwC_class / ExifTool_structure ! !--- property / tag: stored DwC-data

• also classes without (explicitely given) properties Here I miss the one-to-one relationship.

  (A) Reading "Darwin Core quick reference guide" my impression is that e.g. data for "PreservedSpecimen" or "MaterialCitation" is stored like DwC_class: stored DwC-data e.g: PreservedSpecimen: "A plant on an herbarium sheet. A cataloged lot of fish in a jar" MaterialCitation: "A citation of a physical specimen from a scientific collection in ..."

  (B) Looking on Exiftool side I see the following tree ExifTool_structure ! !--- tag e.g: PreservedSpecimen ! !---MaterialSampleID: xxx-data (MaterialCitation is missing at the moment).

Now my question for the "logical structure" is: Is (A) or (B) to be used in order to store DwC-data properly?

Maybe an example that shows one of the "classes without properties" would be helpful.

Thanks for your comments/answers in advance

Best regards herb