Time Marker is a slider indicating the current time, displayed in the Time Ruler. Specifically, it takes the client host time and uses SchedulerOptionsBehaviorBase.ClientTimeZoneId to position the marker on the time ruler. By default, if the SchedulerOptionsBehaviorBase.ClientTimeZoneId is not specified, it is set to the server time zone ID.
Its visibility is determined by the DayView.TimeMarkerVisibility property for all time rulers in the view. To specify time marker visibility for a particular time ruler, use the TimeRuler.TimeMarkerVisibility property.