Citations =? links

I've been thinking a lot about scholarly citation and hyperlinking lately. I've been struggling to test mentally the degree to which the latter can support what I see as the distinct functions of the former:

• attribution of argument or idea
  
• source of fact or quotation
  
• pointer to further information not directly germane to the issue at hand
  
• disambiguation
• classification
  

I'd be grateful for suggested additions to, and refinements of, the list of functions. It would also be helpful to learn of any literature on the subject.

Of course the goal is "computationally actionable citation."