Feed::Parser::RSS::RDF::Extensions
Sometimes people use a few of the RSS 0.92 tags in RSS 1.0 without specifying a different namespace. There is actually an RSS 0.92 namespace for RSS 1.0 but that isn't what's happening here. These are ad-hoc unqualified extensions to RSS 1.0. They suck.
xmlns="http://purl.org/rss/1.0/"