title: How can Order Many-to-Many with Ordered relationships
body: <p>Ordered relationships works great... but i have not found documentation about how can use the check "ordered" in the fetch controller.</p>
  
  <p>My problem is: How i can sort the fetchcontroller? What's the key (SORT_VALUE) to use in <code>-sortDescriptorWithKey:ascending:</code></p>
  
  <p>eg: </p>
  
  <pre><code>NSSortDescriptor *sortPlaylistSongs = [NSSortDescriptor sortDescriptorWithKey:@"SORT_VALUE" ascending:YES];
  </code></pre>
  
  <p>Thank you.</p>