ded by the operating
system's selector. This state is stored in a <code>Sync</code> data structure and
referenced by <a href="struct.Registration.html"><code>Registration</code></a>. When the <a href="struct.Registration.html"><code>Registration</code></a> instance is
dropped, this state is cleaned up. Because the state is stored in a <code>Sync</code>
data structure, the <a href="struct.Registration.html"><code>Registration</code></a> instance is able to be moved to other
threads.</p>
<p>By default, a runt