"op": "c",                                                                                                                                                                                                              
  "o": {                                                                                                                                                                                                                  
    "commitTransaction": 1,                                                                                                                                                                                               
    "commitTimestamp": ...                                                                                                                                                                                  
  },                                                                                                                                                                                                                      
  // New Field
  "m": [
    {"uuid": uuid1, "sz": <int64>, "ct": <int64>},
    {"uuid": uuid2, "sz": <int64>, "ct": <int64>},
    ...
  ]
  ...                                                                                                                                                                                              
}