anchor.diff:  Validity = 40 * Cool URI Score + 60.0 * Linked Data Rule Score
   
   [[performance]]
  -Performance
  -~~~~~~~~~~~
  +=== 2.6 Performance
   
   Performace suggests how powerful the endpoint is.
   
  
positive.code:   \right.$]
  
  [[usefulness]]
  Usefulness
  ~~~~~~~~~~
  
  Usefulness represents the degree how easily we can link data in the
  endpoint. We measure the three metrics:
  
negative.code:   \right.$]
  
  [[validity]]
  === 2.5 Validity
  
  Validity represents how endpoint and data in it obey the rules. We
  measure the two metrics:
  