title: What do the letters mean as Win32api arguments?
body: <p>I'm using the <code>Win32api</code> module. I want to know what the <code>L's</code> and <code>P's</code> mean in the following line:</p>
  
  <pre><code>function = Win32API.new('user32', 'MessageBox', ['L', 'P', 'P', 'L'], 'I')
  </code></pre>
  
  <p>I know that <code>user32</code> is the dll from which the <code>MessageBox</code> function is called from, but what do the <code>L's</code>, <code>P's</code>, and the <code>I</code> do, more specifically what do they stand for?</p>