A string Id that identifies the caller of the method that invoked the event. In most cases the Id will contain the Id of the UI control that invoked the triggering method on WebScheduleInfo. This parameter is optional and may be null.
Requirements
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, 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