http://hl7-fhir.github.io/search says:

In the case of returning container resources, the server SHALL populate the entry.search.mode element so that the client can pick matches and includes apart (the usual approach of doing it by type may not work). If the return type is the contained resource, this must be done slightly differently:

And http://hl7-fhir.github.io/bundle says:

search.mode: An indication of whether the resource is in the search set because it matched the search criteria, or whether it is included because another resource refers to it (e.g. by the _include parameter)

What if a given resource belongs in both? Two solutions would be:

• Specify that, when a resource is present for both purposes, then match takes precedence

• Change this field to multiple cardinality, allowing both match and include to be independently specified