title: What does enabling STL iterator debugging really do?
body: <p>I've enabled iterator debugging in an application by defining</p>
  
  <pre><code>_HAS_ITERATOR_DEBUGGING = 1
  </code></pre>
  
  <p>I was expecting this to really just check vector bounds, but I have a feeling it's doing a lot more than that. What checks, etc are actually being performed?</p>
  
  <p>Dinkumware STL, by the way. </p>