XML Syntax
  - Element type definition using constructors and basic
    types
    
 
 
- Content model for element types:
    
      - Ordered group (connector ',' ) or
        unordered group (connector '&' ) 
- List: occurrence indicators '+' et
        '*'                
- Choice: connector
        '|'                                          
         
- Option: optional indicator '?'
- Identity
        
 
 
 
- Attribute definition attached to element types
    
 
 
- Entity definition (string replacement mechanism)