WeekStart has implications when applying certain rules, like WeekOfYearRecurrenceRule, regarding when the first week of the year starts. First week of the year is considered to be the first week that has at least 4 days in the year.
Note that the default value of this property is Monday.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2