With the history bundle constraint on must having a request/response, should this be an and (for having URLs in fullUrl, request, and response) instead? Same applies to full resource, would the request and response be required at all times for the resource entries? (If servers must populate a request/response in R4, then is it worth it to have the backport-notification-url-location extension?)

Existing Wording:

Each Bundle.entry for id-only notification SHALL contain a relevant resource URL in the fullUrl, request, and/or response elements. The Subscription’s notificationUrlLocation element describes the behavior which should be used.

(Comment 39 - imported by: Gino Canessa)