Composition on the FHIR specification website.
A set of healthcare-related information that is assembled together into a single logical package that provides a single coherent statement of meaning, establishes its own context and that has clinical attestation with regard to who is making the statement. A Composition defines the structure and narrative content necessary for a document. However, a Composition alone does not constitute a document. Rather, the Composition must be the first entry in a Bundle where Bundle.type=document, and any other resources referenced from Composition must be included as subsequent entries in the Bundle (for example Patient, Practitioner, Encounter, etc.).
The body should be a list of valid JSON patches for Composition. For example, to update a Slot status to busy, this would be the body:
[
{
op: 'replace',
path: '/status',
value: 'busy',
},
],