Background: This IG is unique because it describes a foundational set of profiles and associated FHIR Search API. Although this IG provide general guidances over select use cases, These use case are driven by USCDI requirements. For example see the SDOH Guidance for more information when exchanging Social Determinants of Health (SDOH) Service Requests. Nevertheless, the profiles are intended to be used by implementers and IG developers over a broad set of domains and use cases. To allow for this reuse the profiles set the minimum expectation for recording, searching, and fetching and thus contain few required elements and use broad or loosely bound terminologies. The expectation is that the implementer or implementation community will further constrain the US Profile for their particular use case, including limiting the terminology to what is appropriate for their domain. Reasoning: We acknowledge that the ServiceRequest valueset is broad to accommodate a broad set of use cases. However the topic of lab orders is out of scope for this version of US Core and the general expectation is that the implementer or implementation community will further constrain it for their particular domains such as laboratory.   Proposed Changes: Add an implementation note to ServiceRequest Implementation Notes Section: The `ServiceRequest.code` valueset is broad to accommodate a wide variety of use cases and should be constrained to a subset for a particular use case or domain. (for example, LOINC for laboratory orders.)