In context of https://jira.hl7.org/browse/FHIR-28375 we propose that the Reference list be limited to US Core Practitioner Profile and all other base standard choices be optional.

A human being is the primary party of interest as the performer regardless of the organization they are with.  The data source should not be required to just be able to document an Organization.  Therefore, Organization should remain optional with the other choices allowed by the base standard.

As the FHIR US Core profile is used for accessing and exchanging data based on what the source system has, this should not require the data source system to add functionality to capture a patient as part of the diagnostic report for a note.  Additionally, C-CDA does not impose this requirement either.

Links to pages:

http://hl7.org/fhir/us/core/STU3.1/StructureDefinition-us-core-diagnosticreport-note.html

https://build.fhir.org/ig/HL7/US-Core-R4/StructureDefinition-us-core-diagnosticreport-note.html