It seems xkos:Correspondence is close to the notion of skos:ConceptScheme in practical terms - except it will hold xkos:ConceptAssociations : an xkos:Correspondence will have the same administrative metadata as a skos:ConceptScheme (publisher, dates, coverage, etc.), and could follow the same versioning/publishing process as a ConceptScheme, and using xkos:succeeds could be applicable for xkos:Correspondence too.
Explaining how are xkos:Correspondence similar/different from skos:ConceptScheme could be a good thing.
Besides, xkos:compares does not appear on the diagram.
It seems xkos:Correspondence is close to the notion of skos:ConceptScheme in practical terms - except it will hold xkos:ConceptAssociations : an xkos:Correspondence will have the same administrative metadata as a skos:ConceptScheme (publisher, dates, coverage, etc.), and could follow the same versioning/publishing process as a ConceptScheme, and using xkos:succeeds could be applicable for xkos:Correspondence too. Explaining how are xkos:Correspondence similar/different from skos:ConceptScheme could be a good thing.
Besides, xkos:compares does not appear on the diagram.