title: Is this a valid ISO 8601 formatted string?
body: <p>Is the following date string a currently valid ISO 8601 formatted string?</p>
  
  <pre><code>2016-09-18T17:34:02.666Z
  </code></pre>
  
  <p>On the <a href="https://en.wikipedia.org/wiki/ISO_8601" rel="noreferrer">wiki</a> for 8601 I don't see this format, however it is specified <a href="https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString" rel="noreferrer">here</a>.</p>