Property:IsDefinedBy

The attribute isDefinedBy is (rarely) used to specify URLs (or, more generally, URIs), that provide a definition of the item, usually expressed in RDF Schema. This is usually only of interest if the given subject has a strict external definition, in which case the definition can be imported into SMW (see Help:Import vocabulary) making isDefinedBy unnecessary.

In the RDF export, this attribute is represented as rdfs:isDefinedBy (RDF Schema) (see MediaWiki:Smw_import_rdfs). However, in RDF Export, article concepts already get an rdfs:isDefinedBy property.