or'> &para;</a></span></dt>
<dd><p>This procedure returns the number of callbacks posted to an event loop
with the event-post! procedure which at the time still remain queued
for execution.  Amongst other things, it can be used by a calling
thread which is not the event loop thread to determine whether
throttling is likely to be applied to it when calling event-post! -
see the documentation on make-event-loop for further details.
</p>
<p>The &rsquo;loop&rsquo; (event loop) argument is optional: this procedu