Relation pm#relation_to_type (*,pm#type)
supertype: pm#relation_to_collection
subtype: pm#relation_to_class (*,rdfs#class)
subtype: pm#kind__type___class___instance_of__instanceof (?,rdfs#class) the '^' link in the FT notation
subtype: sumo#extension_fn__extensionfn (sumo#Attribute -> sumo#class) a unary_function that maps an attribute into the class whose condition for membership is the attribute