Background: US Core Implementation Guide is based on  FHIR Version R4  and defines the minimum set of constraints on the FHIR resources to create the US Core Profiles. It also defines the minimum set of FHIR RESTful interactions for each of the US Core Profiles to access patient data.  It serves two main audiences: Testers and Implementers for content and guidance specific to Data Query Access for purpose of ONC Certification testing. Implementers and Implementation Communities for using US Core profiles as  the foundation for US Realm FHIR implementation guides.  The rendering of differential tree views of US Core Profile lists only the mandatory and must support element with very few exception related certification testing.   These are design decisions. The addition of this text referenced by  the commenter: An  Observation.component  without a value,  SHALL  include a reason why the data is absent. *Systems that never provide [a]  component observation without a component value are not required to support  Observation.component.dataAbsentReason . ... is part of the latest version update.  We clarified MustSupport for Observation.component.value [x] vs dataAbsentReason -- FHIR-34061  to help both testers and implementers during the certification process.  Reasoning:  We disagree that the component element needs to be rendered in the differential rendering of the profile.  Although  the implementation guidance sections typically focuses on the element in the profile, it also provides more general implementation guidance to aid implementers including testers which may focus on optional elements as well. Proposed Changes: 1) Will expand documentation the purpose of the various sections on the profile pages in the How to read this Guide   and include "Although  the implementation guidance sections typically focuses on the element in the profile, it also provides more general implementation guidance to aid implementers including testers which may focus on optional elements as well."  in there to help the reader better understand the context and content.