o request a
particular signal causes it to be created, and other requests for
the signal return references to the same object.</p>
</dd></dl>

<dl class="describe">
<dt>
<tt class="descname">posted</tt></dt>
<dd><p>Array used internally to stored the post history so that when new
listeners express interests in this signal, they can be informed
of the signals that have been posted so far.  This can be cleared
using the signal&#8217;s <a class="reference internal" href="message.html#Clear" title="Clear"><tt c