title: gnuplot time format variable separated by spaces
body: <p>I have a dataset with columns separated by spaces.  The columns are ' year month day hour data ' in this order. </p>
  
  <p>I have tried several time formats such as "%Y%m%d%H", "%Y%m%d%k", "%Y %m %d %k" but they don't work.  I think it is because the columns change the number of digits.  </p>
  
  <p>Which is the appropiate time format for this kind of data? </p>
  
  <p>Here's an example of the data set.   </p>
  
  <pre><code>   2002  12  31   9    65
     2002  12  31  10    60
     2002  12  31  11    56
     2002  12  31  12    50
     2002  12  31  13    45
     2002  12  31  14    38
     2002  12  31  15    45
     2002  12  31  16    50
     2002  12  31  17    47
     2002  12  31  18    44
     2002  12  31  19    40
     2002  12  31  20    32
     2002  12  31  21    35
     2002  12  31  22    40
     2002  12  31  23    33
     2003   1   1   0    28
     2003   1   1   1    25
  </code></pre>
  
  <p>And here's my code:</p>
  
  <pre><code>     set xdata time
       set timefmt "%Y%m%d%k"
       plot   "datafile.dat" using 1:2  
       set terminal png enhanced  
       set output "series.png"
       replot
  </code></pre>