XML Query Data Model
  - 
    Study existing models
 Node-labeled, tree-constructor models
      - 
	XPath, XML Infoset
      
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	Edge-labeled, graph models with node identity
      
- 
	Semi-structured languages, XML-QL, Lorel
    
 
- 
    Provide formal definition for use by algebra
 Functional notation
- 
    Map from PSV Infoset to Query Data Model in functional notation