Namespaces
- ar: addressable resources
- desc: you go to the URL, and get "the thing" back
 
- thought: should've called it "locatable resource"
 
- features: hierarchically consistent
 
 
- book: since ARs can be books, this probably needs reworking. Also, since some ARs are subclassed by website, website/author, 
 
- community: not exactly an organization; could be used for factions, alliances, etc; differs from group in that a community is a social unit with some common values; a group is just an enumeration with common characteristics
- hierarchically consistent
 
 
- course: educational unit of teaching
 
- email: 
 
- event: