tagging, scope, sweeping statements

Hi all,

Sorry if this has been beaten to death before (I checked the archives, 
honest!) but I'm wondering how to express statements about a *class* of 
URI's, as opposed to just one.  Seemed apropos to all this talk of 
del.icio.us and tagging.

My project can, among other things, display the tags associated with a 
page while you are browsing.  The problem with a del.icio.us-style 
format is that I must infer generalizations: a tag of "news" on 
http://www.cnn.com/ should also apply to a page deep within the site.  
But a tag of "news" on http://news.google.com does NOT apply to every 
page on google.com.

Rules of thumb can get me so far, but something explicit would be far 
better.  I'm currently using something like this:

<item rdf:about="http://news.google.com/">
  <title>Google News</title>
  <link>http://www.google.com/</link>
  <x:scope>*news.google.com/*</x:scope>
  ...

Is there a standardized or more elegant way to express this?  I'm an RDF 
newbie and would appreciate any tips. A project summary is at 
http://getoutfoxed.com/about

-stan