Meaning OfATag A Collaborative Approach to Bridge the Gap

... del.icio.us and Flickr, orbloggingand dedicated agregationwebsites like Technorati ... must respect a given pattern so that the server understand it, which is: tag_uri=SERVER ...

http://events.linkeddata.org/ldow2008/papers/22-passant-laublet-meaning-of-a-tag.pdf