JavaScript question - how does dataTables generate _=1359101216769

Hello,

a very low priority, pure curiosity question :-)

How does dataTables generate the random string of numbers to prevent caching, when fetching JSON data:

91.209.51.140 - - [25/Jan/2013:09:06:59 +0100] "GET /cards-json.php?id=VK72883921&_=1359101216769 HTTP/1.1" 200 255254

Which JavaScript function is it? I failed to find that spot in the jquery.dataTables.js

Thanks
Alex