Canonical instance for the resource SubscriptionTopic. It describes the topic for the Subscription. This topic SHALL be used in all DocumentReference subscriptions that have a specific patient in the criteria element. Note that:

• the trigger for this topic SHALL be the resourceTrigger (so the eventTrigger SHALL NOT be used)
• the resourceTrigger.resource element SHALL be a DocumentReference resource
• this resource SHALL be used when the "DocumentReference Subscription for Full Events Option" is supported
• the events are creation, update and deletion of a DocumentReference

A DocumentReference resource is created, updated or deleted (consider all possible events on DocumentReference).