title: What does "nib" and "xib" stand for?
body: <p>I wonder why that file extension is called <code>nib</code> or <code>xib</code>.</p>
  
  <p>I guess that the <em>ib</em> in <em>nib</em> is <code>Interface Builder</code>. </p>
  
  <p>But the <code>n</code>? Or the <code>x</code>? Any idea?</p>