There is a good thread to read on flickr about machine-tags that you can read here ~ http://www.flickr.com/groups/api/discuss/72157594497877875/ http://www.flic

There is a good thread to read on flickr about machine-tags that you can read here ~ http://www.flickr.com/groups/api/discuss/72157594497877875/ http://www.flickr.com/groups/api/discuss/72157594497877875/ Using rdf you can represent tags as "foo:bar=foobar". So your use is really only limited by the limitations of the format itself.