Once the program is started it will look after the current date and depending on that date it will show the year calendar.
This means that when you start the program at 20120222 at 04:00 ( 20110221 ) it will present you the Tibetan year calendar of 2011.
When you start the program at 20120222 at 05:00 it will present you the Tibetan year calendar of 2012.

The year calendar is based upon the source code from Edward Henning.
See http://www.kalacakra.org/calendar/kcal.htm
The original C code is converted into a C# class which generates XML files for
Phugpa, Tsurphu or Tserab Ling. The class is instructed which tradition to use
for selected years and checks if the XML file is available.
If not the XML file will be created.
In turn these XML files are used to generate the year calendar.