title: Drawing box plot with gnuplot 4.6
body: <p>In the <a href="http://www.gnuplot.info/docs_4.6/gnuplot.pdf" rel="nofollow">official document </a> in page 44 it says, to draw a boxplot</p>
  
  <pre><code># Place a boxplot at x coordinate 1.0 representing the y values in column 5
  plot 'data' using (1.0):5
  </code></pre>
  
  <p>I cannot get it work, when I do above gnuplot only draws  points, not a box. Anybody knows how to do it? In the guide, the example shows a box plot (page 44 the   figure on the right)</p>
  
  <p>I am using gnuplot 4.6 patch level 4. I am not getting any errors, but the box is just not there.</p>
  
  <p>When I use the demo script</p>
  
  <pre><code>plot 'silver.dat' using (1):2, '' using (2):(5*$3)
  </code></pre>
  
  <p>it works, what does the second part after the comma mean? <strong>(  '' using (2):(5*$3) )</strong></p>