Manual:$wgEnableCreativeCommonsRdf

Details
Toggles the inclusion of Creative Commons RDF metadata in page output. See RDF Metadata at Metawiki for more information.

In MediaWiki 1.8.2, the source file Skin.php contains function addMetadataLinks which calls addMetadataLink to add Creative Commons metadata when $wgEnableCreativeCommonsRdf evaluates true, with title Creative Commons and type application/rdf+xml, containing an embedded URL with query item.

When MediaWiki serves a page request with query item  present, function wfCreativeCommonsRdf is called within source file Metadata.php which parses $wgRightsUrl into metadata format.