This is the ValueSet that contains all the codes in CRD Coverage Information Additional Documentation Value Set (http://hl7.org/fhir/us/davinci-crd/ValueSet/AdditionalDocumentation) and CRD Coverage Information Additional Documentation Value Set (http://hl7.org/fhir/us/davinci-crd/ValueSet/AdditionalDocumentation). E.g. what you have to deal with if you get resources containing codes in either of them