http://msmvps.com/blogs/luisabreu/archive/2007/03/21/getting-your-intervals-right-with-the-ajaxtoolkit-timespans.aspxThe AJAXToolkit introduces a Timespan class that lets you do some interesting things with time intervals. After looking at the class (which is defined on the datetime.js file, inside the common folder), it's obvious that it tries to mimic the TimestampenCommunityServer 2008.5 SP2 (Build: 40407.4157)