I was not able to find a link as a follow-up of  "We will talk about the extensions in a future article."

I really appreciate those posts as it illustrates what we would like to put in place: when a patient is created/modified/merged into our EMPI we would like to send anHL7v2 message to a national MPI

I was wondering if in case of new Patient creation or a patient trait modification (not his identifer), thise events initiate also a PIX Notification ?

here we go for the correct syntax:

"basedOn": [
  {
    "identifier": {
      "system": "urn:ietf:rfc:3986",
      "value": "urn:uuid:3aae92e6-9c51-46ab-83bb-bc3a5a66d429"
    },
    "type": "CarePlan"
  }
],