title: MongoDate structure in PHP - JSON output
body: <p>I am currently using MongoDb for an API I am developing. I am trying to figure out what is the  sec and usec property represents in a MongoDate object in PHP.</p>
  
  <p>When I json_encode my output I get the MongoDate interpreted as</p>
  
  <pre><code>created: {
      sec: 1351294929,
      usec: 564000
  }
  </code></pre>
  
  <p>What I want to know is what does "sec" and "usec" represent exactly. In this case "created" is the timestamp when the document is made but does 'sec' represent the Unix timestamp format in seconds? Then what does "usec" represent?</p>
  
  <p>And is it fine to leave the output like this and JS handles intepretation or should I reformat this in the PHP side to a YYYY-MM-DD H:i:s format?</p>