instance_of A relation between an instance and a class. For components: a primitive relation between a component instance and a class which it instantiates at a specific time. For processes: a primitive relation, between a process instance and a class which it instantiates, holding independently of time. OBO_REL:instance_of The instance_of relationship is considered axiomatic by the obo file format specification; ie it is taken for granted. The is_a relation is still included in this ontology for completeness. mosquito_insecticide_resistance_ontology