This is the ValueSet that contains all the codes in Payer source of data (http://hl7.org/fhir/us/davinci-pdex/ValueSet/ProvenancePayerSourceFormat) and Payer source of data (http://hl7.org/fhir/us/davinci-pdex/ValueSet/ProvenancePayerSourceFormat). E.g. what you have to deal with if you get resources containing codes in either of them