rdfs:comment MUST be either http://open-services.net/ns/core,#Exactly-one, http://open-services.net/ns/core#Zero,-or-one, http://open-services.net/ns/core#Zero-or
rdfs:comment Should be http://open-services.net/ns/core,#Reference, http://open-services.net/ns/core#Inline or, http://open-services.net/ns/core#Either