This case-insensitive code system http://hl7.org/fhir/us/davinci-pdex/CodeSystem/ProvenancePayerDataSource defines the following codes:

Code	Display	Definition
hl7v2other	HL7 v2	HL7 v2 Message
hl7v2oru	HL7 v2 ORU	HL7 v2 Structured Observation Report(ORU) message
hl7v2adt	HL7 v2 ADT	HL7 v2 Admit, Discharge Transfer (ADT) message
hl7v2r01	HL7 v2 R01	HL7 v2 Observation (R01) message
hl7v2rsp	HL7 v2 RSP	HL7 V2 Immunization Record Response
hl7v2orm	HL7 v2 ORM	HL7 v2 Orders
hl7v2mdm	HL7 v2 MDM	Medical Document Management
hl7v2vxu	HL7 v2 VXU	HL7 V2 Immunization Transaction
hl7v3	HL7 v3	HL7 v3 Message
hl7ccda	HL7 C-CDA	HL7 Consolidated-Clinical Document Architecture
hl7cda	HL7 CDA	HL7 CDA documents that are not C-CDA
hl7cdaqrda	HL7 CDA QRDA	HL7 Quality Reporting Document
hl7fhirdstu2	FHIR DSTU2	HL7 FHIR DSTU2
hl7fhirdstu3	FHIR STU3	HL7 FHIR STU3
hl7fhirr4	FHIR R4	HL7 FHIR R4
x12837	837 claim	X12 837 Claim
x12278	278	X12 Prior Authorization
x12275	275	X12 Attachment
x12other	X12	X12 non-specific transaction
script	NCPDP SCRIPT	National Council for Prescription Drug Programs (NCPDP) SCRIPT message (eRx)
ncpdp	NCPDP Telecommunication	NCPDP Telecommunication transaction (pharmacy claims)
capture	Direct Capture	Direct Capture, such as into a payers case management system
customtx	Trading Partner Format	Trading Partner Proprietary format
image	Image	Fax or scanned document
unstructured	Unstructured Document	PDF, text and other unstructured document
other	Other	Any other document format not specifically defined