title: Can I plot times when they're given as UNIX timestamps with added milliseconds?
body: <p><em>I'm using gnuplot 4.4 on CentOS 6.6.</em></p>
  
  <p>I've found many <a href="https://newspaint.wordpress.com/2013/09/16/millisecond-time-resolution-scatter-plotting-with-gnuplot/" rel="nofollow">example</a>s online showing that the following (note the use of <code>%.3S</code>) will enable timestamps like "<code>12:42:51.047</code>" to be parsed and used as X axis values:</p>
  
  <pre><code>set xdata time
  set format x "%H:%M:%.3S"
  set timefmt "%H:%M:%S"
  </code></pre>
  
  <p>However, my input is not like <code>HH:MM:SS.mmm</code> but like <code>SSSSSSSSSS.mmm</code>, where the integral part is a UNIX timestamp.</p>
  
  <p>I tried the following, but the parsing appeared to have failed since all datapoints rendered at "00:00:00":</p>
  
  <pre><code>set xdata time
  set format x "%.3s"
  set timefmt "%H:%M:%S"
  </code></pre>
  
  <p><a href="http://www.gnuplot.info/docs_4.4/gnuplot.pdf" rel="nofollow">The manual</a> doesn't give any indication that this is possible but, then again, it doesn't say that the <code>%H:M:%.3S</code> was going to work, either.
  Is it possible to do what I want to do? If so, how?</p>