When you call date-related functions, you can use the following enumeration members in your code in place of the actual values.
Some date-related functions take a DayOfWeek argument, a WeekOfYear argument, or both. The FirstWeekOfYear enumeration specifies the valid values for the WeekOfYear arguments, as well as the possible return values from the functions.
The WeekOfYear argument takes the FirstWeekOfYear enumeration members.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)