title: Why must rdf:dataType subclass rdf:Class in RDF?
body: <p>From <a href="http://www.w3.org/TR/rdf-schema/" rel="nofollow">RDF Schema 1.1</a></p>
  
  <blockquote>
    <h2><a href="http://www.w3.org/TR/rdf-schema/#ch_datatype" rel="nofollow">2.4 rdfs:Datatype</a></h2>
    
    <p>rdfs:Datatype is the class of datatypes. All instances of
    rdfs:Datatype correspond to the RDF model of a datatype described in
    the RDF Concepts specification [RDF11-CONCEPTS]. rdfs:Datatype is both
    an instance of and a subclass of rdfs:Class. Each instance of
    rdfs:Datatype is a subclass of rdfs:Literal.</p>
  </blockquote>
  
  <p>Why must <strong>rdfs:Datatype</strong> subclass <strong>rdf:Class</strong>? Why can't it just be an instance of <strong>rdfs:Class</strong>? I don't understand the meaning of subclassing class.</p>