text: A restriction always describes a class. Sometimes (as we will soon see) it can be a defined class. 
  Other times it may be an anonymous class. In all cases the class contains all of the individuals 
  that satisfy the restriction, i.e., all of the individuals that have the relationships required to be a 
  member of the class. In section 9.2 one of our SPARQL queries will return several anonymous 
  classes. 