Background The commenter is referring to the US Core DocumentReference Category which is defined as "The US Core DocumentReferences Category Value Set is a ‘starter set’ of categories supported for fetching and storing clinical notes." and includes a single concept Clinical-note http://hl7.org/fhir/us/core/CodeSystem/us-core-documentreference-category   US Core DocumentReference Profile's Profile Specific Implementation Guidance  also states: In addition to the  US Core DocumentReference Category  value set, other category schemes such as the LOINC-based  Document Class Value Set  and  IHE XDSclassCode  may be used to facilitate the sharing of health documents. Although it is unclear if the commenter is proposing it, if implemented, it would be treated as a hierarchical ValueSet to include a subset of codes from the LOINC-based Document Class Value Set in   the existing code.   Rationale We recognize the value in finer-grained categories for some users. However, because there are technical complexities and challenges for implementers to support additional categories, we need to demonstrate wide adoption by the community before updating this valueset.  Note that  implementers and other guides can support other categories for their use cases.