Current language: "...Many of the profiles in this guide reference other FHIR resources that are also US Core Profiles. These references are defined in the formal profile definitions. For example, US Core CareTeam Profile references US Core Patient. For any other references to base FHIR resources¹ or not formally defined in a US Core Profiles, the referenced resource SHOULD be a US Core Profile if a US Core Profile exists for the resource type. For example, although Condition.asserter is not constrained by this guide, the reference to Patient or Practitioner SHOULD be a valid US Core Patient or US Core Practitioner."

Current language does not clearly articulate why some profiles reference US Core profiles while others do not. Consider revising for clarity to something like: "Many of the profiles in this guide reference other FHIR resources that are also profiled by US Core. In some cases, US Core profiles constrain these references to point to the relevant US Core profile rather than the base FHIR resource. For example, US Core CareTeam Profile references US Core Patient. However, to improve readability of US Core profiles, we did not change every possible reference where a relevant US Core profile exists; doing so would add clutter to the differential view of the profile. For any references to base FHIR resources¹ in a US Core profile, US Core Responders SHOULD return references to resources that conform to a US Core profile if a US Core profile exists for the resource type. For example, although Condition.asserter is not constrained by this guide, the reference to Patient or Practitioner SHOULD be a valid US Core Patient or US Core Practitioner."