title: How to add child columns / divide columns in datatables.js
body: <p>I have a dataset with child columns. How can I emulate using datatables.js? <br>
  <strong>Ex:</strong></p>
  
  <pre><code>+-------+----------------------------+-----------+
  | Name  | Marks                      | Rank      |
  |       +---------+----------+-------+           |
  |       |Internal | External | Total |           |
  +-------+---------+----------+-------+-----------+
  | Sandy |  24     |  55      | 79    |Distinction| 
  +-------+---------+----------+-------+-----------+
  | Bill  |  13     |  25      | 38    | Fail      |
  +-------+---------+----------+-------+-----------+
  </code></pre>
  
  <p>Currently I am using <a href="https://datatables.net/examples/basic_init/complex_header.html" rel="nofollow">this</a>, but when I save the table as csv / xls, I get</p>
  
  <pre><code>+------------------------------------------------+
  | Name  |Internal | External | Total | Rank      |
  |------------------------------------------------|
  | Sandy |  24     |  55      | 79    |Distinction| 
  |------------------------------------------------|
  | Bill  |  13     |  25      | 38    | Fail      |
  +------------------------------------------------+
  </code></pre>
  
  <p>But we have an option of adding <a href="https://datatables.net/examples/api/row_details.html" rel="nofollow">child rows</a>.</p>
  
  <p><strong>Is there any way to have child columns? Or can we divide a column?</strong></p>