Care Plan includes references to a variety of request activities, but it also has a “detail” structure for codes, reasons, performers, etc. that can be used if you have the data fields but not the resource.

The idea seems to be to support applications that don't support the referenced resource types. However, it's not clear that it is easier to write to a backbone than to a contained resource. If it's not significantly easier, then having two different ways to represent the same thing is bad.

(Neither backbone nor contained resource can be identified or given provenance. It was suggested that you can’t search on a contained resource, but the Detail elements aren’t in the Search Parameters.)

chat: https://chat.fhir.org/#narrow/stream/220328-Care-Plan.2FCare.20Coordination/topic/Is.20Detail.20Useful/near/224529313