https://qudt.org/schema/qudt/QuantityKind is not a subclass of skos:Concept; there was a discussion whether to make it and it was rejected.
If our QuantityKind is equivalentClass to the QUDT one, then we shouldn't declare it subclass of skos:Concept.
On the other hand, we use skos:broader to make a hierarchy, just like QUDT does. I asked in https://github.com/qudt/qudt-public-repo/issues/719 to remove the declared hierarchy properties qudt:specialization/generalization, for avoidance of doubt.
Suggested simplest way to resolve the issue: make aec3po:QuantityKind a subclass of qudt:QuantityKind , instead of making it equivalent
Implemented in commit 034f375
https://qudt.org/schema/qudt/QuantityKind is not a subclass of skos:Concept; there was a discussion whether to make it and it was rejected. If our QuantityKind is equivalentClass to the QUDT one, then we shouldn't declare it subclass of skos:Concept.
On the other hand, we use skos:broader to make a hierarchy, just like QUDT does. I asked in https://github.com/qudt/qudt-public-repo/issues/719 to remove the declared hierarchy properties qudt:specialization/generalization, for avoidance of doubt.
https://github.com/Accord-Project/aec3po/blob/5fb6f7e2b8b9f0f208caeeab68461aa8b3c0dfcd/src/quantity_kinds.ttl#L27