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.