ecial>&lt;</span><span class=identifier>record_year</span><span class=special>&gt;</span> <span class=comment>// sorted by record's year</span>
  <span class=special>&gt;</span>
<span class=special>&gt;</span> <span class=identifier>record_log</span><span class=special>;</span>
</pre></blockquote>

<p>
<a href="../examples.html#example6">Example 6</a> in the examples section
applies some user-defined key extractors in a complex scenario where
keys are accessed via pointers.
</p>

<h2><a name="composite_keys