From http://www.w3.org/TR/PR-rdf-schema/ It is said about properties that "If there is no domain property, it may be used with any resource". It is also said that "All things being described by RDF expressions are called resources, and are considered to be instances of the class rdfs:Resource". In figure 3, we can see that #type has the domain #Resource. But in the XML serialization, it is listed with no domain at all. This is ok, because it is the same thing, from the rules above. But why is #type the ONLY property to lack #domain? #label and #comment has it explicitly stated that their #domain is #Resource. The same could be asked about all these classes that is said to be a sub class of #Resource. From above, you can read that EVERYTHING implicitly has the #type #Resource. So why say that some class is #subClassOf #Resource? All members of the class will already be a resource, regardless of wether the class has subclassed it. Couldn't it be said that #Resource is the base class for all other classes? And wouldn't you save considerble space and effort in the long run, to just make all classes implicitly a subclass to #Resource?