title: nnoremap <C-k> <C-w>k in vimrc
body: <p>I have the following line in my .vimrc.</p>
  
  <pre><code>nnoremap &lt;C-h&gt; &lt;C-w&gt;h
  nnoremap &lt;C-j&gt; &lt;C-w&gt;j
  nnoremap &lt;C-k&gt; &lt;C-w&gt;k
  nnoremap &lt;C-l&gt; &lt;C-w&gt;l
  </code></pre>
  
  <p>The first two lines lets me toggle between top window and bottom window in split mode of vim.
  What does the other two keys do?</p>
  
  <pre><code>&lt;C-k&gt; and &lt;C-l&gt;
  </code></pre>
  
  <p>I have tried them.It doesn't seem to do anything.</p>