Not sure what this JS code is doing
<p>I was given this JavaScript code snippet to implement on a site.  Just sticking it in is not working.  I feel if i can better understand what this code is doing then i could make it work.  Could someone please explain roughly what this code is doing?  Thanks!</p>

<pre><code>&lt;script type="text/javascript"&gt;
var thisref = document.referrer.replace(/&amp;/g, "zzzzz");
var ciJsHost = (("https:" == document.location.protocol) ? "https://" : "http://");
document.write(unescape("%3Cscript src='" + ciJsHost + "tracking.callmeasurement.com/clickx/click_matrix.cfm?munique=" + new Date().getTime() + "&amp;prev=" + thisref + "' type='text/javascript'%3E%3C/script%3E"));
&lt;/script&gt;
</code></pre>
