Existing Wording
The composition section defines a section (or sub-section) of the document, but unlike in CDA, the section content is actually a reference to another resource that actually holds both the narrative and data content for the section. This design means that the narrative and data can be reused in many other ways. Note that the most common resource to use for the content of a section is the List resource.

Proposed Wording
The composition section defines a section (or sub-section) of the document. Like CDA, the section contains the human readable narrative (text). It will also contain a set of references to the underlying resources that were used to construct the text. This design supports the reuse of resources while enabling the construction of authenticated text within documents.

A composition can be authenticated as needed and when dealing with a narrative document, the composition as a whole needs to be reviewed.

Comments
The FHIR document model presumes that the parts (resources) in a document can be removed safely from a document. This may be true for structured data, e.g. "CCD", which was extracted from an EMR, however for narrative documents, authored by physicians and authenticated, the whole is the only safe unit of consumption. For CDA a sense of wholeness is one of the defining characteristics, which has been omitted from the FHIR Document model.

Grahame's Comments
It's not true that wholeness is impacted. In fact, it's explicitly stated - that a FHIR Document has wholeness. Just like with CDA, parts can be excerpted, but they are excerpted. The technical arrangement of the parts makes no contribution to the rules and/or behaviour

Disposition
Not Persuasive

Disposition Comment
Content in CDA documents is frequently sourced from v2 and other sources and is frequently extracted from CDA documents and used within EHRs for other purposes. FHIR is no different in that. The document must still be retained as a cohesive whole.