BIBFRAME Vocabulary The BIBFRAME Vocabulary is a RDF ontology that defines subjects, predicates (properties), and objects and starting with the most general class called a Resource. The Resource class has four main sub-classes: Work - reflects the conceptual essence of the cataloging resource Instance - reflects the individual, material embodiment of the Work Authority - reflects the key authority concepts having defined relationships with Works and Instances. Annotation - a resource that enhances the knowledge about another resource