Sometimes one wants to relate a Property to an Individual itself without telling that this is a reflexive Property. Only by saying that one wants to define a Class that is defined on a Property which in general is also reflexive, but in this case one says that only these members belong to where the property is restricted to an Individual that belongs to this Class itself.
For instance one can say that a Philosopher is someone how knows him/herself, besides other people. This can be done with the Property Restriction
owl:hasSelf which enables the Restriction on Reflexive Properties. So here one does a Class Definition where one restricts the Property
knows to only these Members that are already in the Class, which means a Philosopher is someone who knows himself.
hasSelf is not a Class, but as a Property that is defined to be True, which is written in quotation marks and of the XML Schema Datatype Boolean value True.