<dxsch:SchedulerControl.AppointmentItems>
    <!--An appointment is set every 10 minutes. Five occurrences.-->
    <dxsch:AppointmentItem 
        Type="Pattern"
        Start="1/1/2020 13:00:00"
        End="1/1/2020 14:00:00"
        Subject="Every 10 minutes. Five occurrences."
        RecurrenceInfo="{dxsch:RecurrenceMinutely Start='1/1/2020 13:00:00', Interval=10, OccurrenceCount=5}" />
    <!--An appointment is set every 45 minutes. Infinite (no end time).-->
    <dxsch:AppointmentItem 
        Type="Pattern"
        Start="1/1/2020 13:00:00"
        End="1/1/2020 14:00:00"
        Subject="Every 45 minutes. Infinite."
        RecurrenceInfo="{dxsch:RecurrenceMinutely Start='1/1/2020 13:00:00', Interval=45}" />
    <!--An appointment is set every 20 minutes. The appointment chain duration is 10 hours.-->
    <dxsch:AppointmentItem 
        Type="Pattern"
        Start="1/1/2020 13:00:00"
        End="1/1/2020 14:00:00"
        Subject="Every 20 minutes. Series duration is 10 hours."
        RecurrenceInfo="{dxsch:RecurrenceMinutely Start='1/1/2020 13:00:00', Interval=20, End='1/1/2020 23:00:00'}" />
</dxsch:SchedulerControl.AppointmentItems>

public AppointmentItem CreateAppointmentPattern(string subj, int categoryId) {
    AppointmentItem apt = new AppointmentItem(AppointmentType.Pattern);
    apt.Start = DateTime.Today.AddHours(9);
    apt.End = apt.Start.AddMinutes(5);
    apt.Subject = subj;
    apt.LabelId = categoryId;
    return apt;
}
    // An appointment is set every 10 minutes. Five occurrences.
    AppointmentItem apt1 = CreateAppointmentPattern("Every 10 minutes. Five occurrences.", 0);
    apt1.SetRecurrenceInfo(RecurrenceBuilder.Minutely(apt1.Start, 5).Interval(10).Build());
    scheduler.AppointmentItems.Add(apt1);

    // An appointment is set every 45 minutes. Infinite (no end time).
    AppointmentItem apt2 = CreateAppointmentPattern("Every 45 minutes. Infinite", 0);
    apt2.SetRecurrenceInfo(RecurrenceBuilder.Minutely(apt2.Start).Interval(45).Build());
    scheduler.AppointmentItems.Add(apt2);

    // An appointment is set every 20 minutes. The appointment chain duration is 10 hours.
    AppointmentItem apt3 = CreateAppointmentPattern("Every 20 minutes. Series duration is 10 hours.", 0);
    apt3.SetRecurrenceInfo(RecurrenceBuilder.Minutely(apt3.Start, apt3.Start.AddHours(10)).Interval(20).Build());
    scheduler.AppointmentItems.Add(apt3);

Public Function CreateAppointmentPattern(ByVal subj As String, ByVal categoryId As Integer) As AppointmentItem
    Dim apt As New AppointmentItem(AppointmentType.Pattern)
    apt.Start = Date.Today.AddHours(9)
    apt.End = apt.Start.AddMinutes(5)
    apt.Subject = subj
    apt.LabelId = categoryId
    Return apt
End Function
    ' An appointment is set every 10 minutes. Five occurrences.
    Private apt1 As AppointmentItem = CreateAppointmentPattern("Every 10 minutes. Five occurrences.", 0)
    apt1.SetRecurrenceInfo(RecurrenceBuilder.Minutely(apt1.Start, 5).Interval(10).Build())
    scheduler.AppointmentItems.Add(apt1)

    ' An appointment is set every 45 minutes. Infinite (no end time).
    Dim apt2 As AppointmentItem = CreateAppointmentPattern("Every 45 minutes. Infinite", 0)
    apt2.SetRecurrenceInfo(RecurrenceBuilder.Minutely(apt2.Start).Interval(45).Build())
    scheduler.AppointmentItems.Add(apt2)

    ' An appointment is set every 20 minutes. The appointment chain duration is 10 hours.
    Dim apt3 As AppointmentItem = CreateAppointmentPattern("Every 20 minutes. Series duration is 10 hours.", 0)
    apt3.SetRecurrenceInfo(RecurrenceBuilder.Minutely(apt3.Start, apt3.Start.AddHours(10)).Interval(20).Build())
    scheduler.AppointmentItems.Add(apt3)