I am trying to understand if there a unique identifier for transactions. I didn't find anything about that mentioned in listsinceblock's help.
{
"involvesWatchonly": true,
"account": "",
"address": "mvd6qFeVkqH6MNAS2Y2cLifbdaX5XUkbZJ",
"category": "receive",
"amount": 10,
"label": "",
"confirmations": 69,
"blockhash": "62967ce950fc03b14179e58f42e426b63cbfbf63c2b9e59acb6a719a09c23b94",
"blockindex": 58,
"blocktime": 1524872287278,
"txid": "aac9b2d7bb7b3476a83a5ac0c2fe21625bcd961ed43a5c5fd3eacf6536dc81d5",
"vout": 7,
"walletconflicts": [],
"time": 1524872276635,
"timereceived": 1524872276635,
"bip125-replaceable": "no"
},