Consequences of User principles :
  - Functionality: 
    
      - deliver a functional presentation for any adequate access
      mechanism
 
 
- Incompatible Access Mechanism: 
    
      - deliver a functional presentation of an error message for
        inadequate access mechanism
 
Let the author make customized presentation :
  - Customization : 
    
      - possibility to provide a customized presentation for any or
        specific delivery context