{
  "resourceType" : "MessageHeader",
  // from Resource: id, meta, implicitRules, and language
  // from DomainResource: text, contained, extension, and modifierExtension
  "timestamp" : "<instant>", // R!  Time that the message was sent
  "event" : { Coding }, // R!  Code for the event this message represents
  "response" : { // If this is a reply to prior message
    "identifier" : "<id>", // R!  Id of original message
    "code" : "<code>", // R!  ok | transient-error | fatal-error
    "details" : { Reference(OperationOutcome) } // Specific list of hints/warnings/errors
  },
  "source" : { // R!  Message Source Application
    "name" : "<string>", // Name of system
    "software" : "<string>", // Name of software running the system
    "version" : "<string>", // Version of software running
    "contact" : { ContactPoint }, // Human contact for problems
    "endpoint" : "<uri>" // R!  Actual message source address or id
  },
  "destination" : [{ // Message Destination Application(s)
    "name" : "<string>", // Name of system
    "target" : { Reference(Device) }, // Particular delivery destination within the destination
    "endpoint" : "<uri>" // R!  Actual destination address or id
  }],
  "enterer" : { Reference(Practitioner) }, // The source of the data entry
  "author" : { Reference(Practitioner) }, // The source of the decision
  "receiver" : { Reference(Practitioner|Organization) }, // Intended "real-world" recipient for the data
  "responsible" : { Reference(Practitioner|Organization) }, // Final responsibility for event
  "reason" : { CodeableConcept }, // Cause of event
  "data" : [{ Reference(Any) }] // The actual content of the message
}