For testing, please provide specific guidance on how to determine per-field matches when those matches are based on codes. It's these per-field matches that inform the scoring rubrics in the table in 4.7.

Assuming I have the client's requested Patient and the server's matched Patient resource, I can inspect them to see which fields match, but I need to determine when the specific conditions in the table are met. Here are what I have so far; please correct and add as necessary, and add this to the IG.

• Responder's MRN: Patient.identifier.type.coding.system == 'http://terminology.hl7.org/CodeSystem/v2-0203' AND Patient.identifier.type.coding.code == 'MR'
• Responder's MPI: Was this meant to be NPI? If so, Patient.identifier.system == 'http://hl7.org/fhir/sid/us-npi'
• Responder's known Digital Identifier: Would an example here be a person ID from an IdP that both systems know? If so, then is there a way to know this from just looking at the Patient.identifier?
• Driver's License Number and Issuing US State: Patient.identifier.type.coding.system == 'http://terminology.hl7.org/CodeSystem/v2-0203' AND Patient.identifier.type.coding.code == 'DL' AND both identifiers have the same Patient.identifier.system, which would specify the Issuing US State, e.g. urn:oid:2.16.840.1.113883.4.3.12, from here
• Passport Number and Issuing Country: Patient.identifier.type.coding.system == 'http://terminology.hl7.org/CodeSystem/v2-0203' AND Patient.identifier.type.coding.code == 'PPN' AND both identifiers have the same Patient.identifier.system, which would specify the Issuing Country, e.g. http://hl7.org/fhir/sid/passport-AUS, from here
• Insurance Member Identifier and Payer ID: Not sure; is there a code that could go in Patient.identifier.type.coding? If not, is this a matter of enumerating the known systems for payers and looking for them in Patient.identifier.system?
• Insurance Subscriber Identifier and Payer ID: Not sure; see above
• Social Security Number: Patient.identifier.system == 'http://hl7.org/fhir/sid/us-ssn'
• SSN (last 4): Not sure; I've seen discussion but no clear guidance