Issue:

Implementers need clear and specific guidance on how to map elements in the US Realm Header to elements in the FHIR Composition especially where extensions are required on the FHIR Composition.  This mapping needs to take the use of the FHIR Provenance Resource into consideration to maximize the fit of the information and the intended semantic meaning of the information that is expressed in a C-CDA document's header.

Proposed Resolution:

Add mapping guidance between the US Realm Header and the FHIR Profile on Composition plus FHIR Profile on Provenance.  Note, in some cases a specific C-CDA Document Template provides additional header constraints over an above what is specified in the US Realm Header Template.  Mappings for the nuanced header constructs of each document type need to be included in the supplied header mapping guidance.