has_contributor created_by As an example, consider the assertion that "Variant X causes Disease Y". At an abstract level this represents a bfo: information content entity (or frbr:Work). This abstract assertion can be concretized / encoded various formats - e.g. a free-text sentence, an rdf graph, a blob of json, or stanza of XML. Each such manifestation might use a different model or structure to represent this knowledge. Each such concrete form is considered a separate resource/digital artifact at the 'manifestation' level, but each expresses the same knowledge. The authored_by and date_authored properties allow us connect an abstract or concrete representation of this assertion to who and when the knowledge was originally generated. This will be the same agent and date for all formats/manifestations listed above. The created_by and date_created properties allow us to connect a representation of the abstract or concrete assertion to who and when the specific manifestation was created in a particular format. The agent/dates here will be different for each of the formats/manifestations listed above. A relation between a particular information resource / digital artifact and an agent who made a primary contribution to its original creation. With respect to information resources, this property is used to capture a creator of a particular representation/manifestation of the information content - e.g. as a web resource or digital artifact. To describe the creator of the information content carried by such a digital artifact or resource, us the 'authored_by' property.