The purpose and use of individual (CompartmentDefinition) instances is not well defined leading to inconsistent membership (via search parameters) across resources. This is further exacerbated by the fact that the individual resources are managed by different workgroups. Without a consistent set of rules as to what should be included in a compartment, it is not clear what a compartment should contain and what is won't be consistent.

The Patient Care WG was reviewing https://jira.hl7.org/browse/FHIR-37840 and looking at adding several elements (and adding related search parameters) that had references to the Patient resource including:

• AdverseEvent recorder
• CarePlan custodian
• Flag author

The AdverseEvent recorder can be a patient resource, but does not necessarily have to be the subject. Should the the resource be considered as part of the patient's compartment event when they are related to it only administratively (as opposed to being a subject)? 

There are several resource inclusion criteria that do this currently, like Condition.participant-actor, MedicationAdministration.performer, ServiceRequest.performer and more. Should AdverseEvent.participant-actor also be included? 

Should all references to Patient be part of the Patient Compartment (which would also require search parameters for each)? Should it only be all references to Patient for the selected resources? If either of these are true, then there should be a rule or a publisher check to verify that it is being done (or at least warn if it isn't).

If it shouldn't be all references to Patient, then is it only certain kinds of references to patient (e.g. participant-actor, recorder, performer, etc.)? 

If it isn't any of the above, then some sort of rules or logic should be defined to better define what should be included.