{
  "uuid": "urn:mrn:signalk:uuid:c0d79334-4e25-4245-8892-54e8ccc8021d",
  "propulsion": {
    "instance0": {
      "label": "Main Engine - The Olde Faithful",
      "revolutions": {
        "value": 1280,
        "timestamp": "2014-08-15T19:00:15.402Z",
        "$source": "foo.bar",
        "meta": {
          "units": "Hz"
        }
      }
    }
  }
}