Background: See the commenter Description The Section that the commenters is referencing is (highlighted text for emphasis): Resource Profile: US Core MedicationRequest Profile ...   Mandatory and Must Support Data Elements The following data-elements must always be present ( Mandatory  definition]) or must be supported if the data is present in the sending system ( Must Support  definition). They are presented below in a simple human-readable explanation. Profile specific guidance and examples are provided as well. The  Formal Profile Definition  below provides the formal summary, definitions, and terminology requirements. Each MedicationRequest must have: ... Each MedicationRequest must support: ... the  reported  flag or reference signaling that information is from a secondary source such as a patient ... ... The MedicationRequest resource can represent that information is from a secondary source using either a boolean flag or reference in  MedicationRequest.reportedBoolean , or a reference using  MedicationRequest.reportedReference  to Practitioner or other resource.  [There is however a typo in the guidance addressed by  FHIR-35935  as a technical correction.] Although both are marked as must support, the server system is not required to support both a boolean and a reference, but  SHALL  support at least one of these elements. The client application  SHALL  support both elements. ...    and the StructureDefinition tree view : Regarding providing guidance to non must support items, see the Resolution Description for FHIR-34971 Reasoning: We agree that the guidance could be clarified Proposed Changes: change : "The MedicationRequest resource can represent that information is from a secondary source using either a boolean flag  or a reference using MedicationRequest.reportedReference to Practitioner  or other resource ."   to: "The MedicationRequest resource can represent that information is from a secondary source using either a boolean flag  or a reference using MedicationRequest.reportedReference"