Revise ambiguous `dct:type` mapping on Data Service

[jakubklimek]

Problem statement

In GeoDCAT-AP 2.0.0 dct:type on Data Service is used in three different contexts.

1. service category with "Classification of spatial data services" code list
2. service type with "Spatial data service types" code list
3. type with "Resource types" code list. (this one also appears in Dataset)

This makes correct assignment of usage notes, labels and the required code lists rather difficult, as well as consequent validation e.g. via SHACL. The current approach is not in line with the profiling guidelines established in the context of the SEMIC Style Guide property reuse guideline Reuse of a property with terminological adaptations and Reuse of a property with semantic adaptations. Also, the approach becomes even more problematic in a cross-profile environment where incompatible requirements can be easily made.

Proposal

Introduce subproperties of dct:type

1. geodcatap:serviceCategory for "Classification of spatial data services" code list
2. geodcatap:serviceType for "Spatial data service types" code list
3. geodcatap:resourceType for "Resource types" code list with the domain of dcat:Resource to accomodate both for Datasets and Data Services

This approach is in line with the profiling guidelines established in the context of the SEMIC Style Guide property reuse guideline Reuse of a property with terminological adaptations and Reuse of a property with semantic adaptations. If interoperability is a concern, a data publisher can always easily materialize the subPropertyOf inference and replace the subproperties with dct:type.