{description: The US Core DocumentReference Type Value Set includes all LOINC  values whose SCALE is DOC in the LOINC database and the HL7 v3 Code System NullFlavor concept 'unknown', package_name: hl7.fhir.us.core, name: USCoreDocumentReferenceType, type: null, package_version: 6.1.0-snapshot1, class: unknown, kind: null, url: 'http://hl7.org/fhir/us/core/ValueSet/us-core-documentreference-type', version: 6.1.0-snapshot1}