er <code class="code">'!'</code>,
    <code class="code">'A'</code>, <code class="code">'B'</code>, or <code class="code">'C'</code>. If atomicity is required, then the user must
    implement their own synchronization (for example, using <a href="Mutex.html#TYPEt"><code class="code">Mutex.t</code></a>).</p>

<h3 id="bytes_data_race">Data races</h3>
<p>If two domains only access disjoint parts of a byte sequence, then the
    observed behaviour is the equivalent to some sequential interleaving of the
    op