pending messages are processed, no timeout will occur. The timeout starts when the message handler for the last pending message returns.</dd></dl>
<dl class="section warning"><dt>Warning</dt><dd>If you re-use message handler code between subscriptions with and without timeouts, keep in mind that the message passed in the message handler may be <code>NULL</code>.</dd></dl>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">sub</td><td>the location where to store