range of dcterms:relation subproperties

[rob-metalinkage]

dcterms:relation
rdf:type rdf:Property ;
dcterms:description "Recommended best practice is to identify the related resource by means of a string conforming to a formal identification system. "@en-us ;
rdfs:subPropertyOf http://purl.org/dc/elements/1.1/relation ;
skos:note "This term is intended to be used with non-literal values as defined in the DCMI Abstract Model (http://dublincore.org/documents/abstract-model/). As of December 2007, the DCMI Usage Board is seeking a way to express this intention with a formal range declaration."@en-us ;
.

The DCMI has a lot of stuff but is unclear about this.

DCAT version 2 has things like dct:source "DataCite resource types"@en ; which probably doesnt match.

it seems that forcing ^^xsd:anyURI is too strict and a proper URI should be allowed, and the spec allows strings in general.