Given either a URL or an entry ID (see below), mltfo.pl first builds a list of TrackBack pings for that entry. It then follows those pings back to the site from which they were sent and finds the TrackBack embedded RDF. From this RDF it looks for the MT category name in dc:subject. It then searches for the site's RSS file, trying first to use auto-discovery, then starting back at the base URI and looking for index.rdf at each path segment (for example, http://www.foo.com/index.rdf, http://www.foo.com/bar/index.rdf, etc). It then fetches the RSS feed and scans that for items in the same category as the original item.