title: Timestamp in SNS -> SQS message body
body: <p>I have an SQS queue subscribed to an SNS topic. When I publish a message to the topic and subsequently receive it from the queue, the message body contains my published message wrapped in some metadata added by SNS, as per <a href="https://stackoverflow.com/questions/10898538/amazon-sns-sqs-message-body">"Amazon SNS -> SQS message body"</a>. Unlike the poster of that question, I want the metadata, as it allows me to generate some latency metrics.</p>
  
  <p>However, I could find nothing in Amazon's documentation or elsewhere on the Googleable web explaining precisely what the metadata means. In <a href="http://docs.aws.amazon.com/sns/latest/dg/SendMessageToSQS.html" rel="nofollow noreferrer">Sending Amazon SNS Messages to Amazon SQS Queues</a>, the Amazon docs give an example of the metadata but do not explain it.</p>
  
  <p>Does anyone know what time the <code>Timestamp</code> field in the metadata is representing? Please provide a citation if possible, because it is really important to me that my understanding is accurate.</p>