public void RRULE1()
        {
            iCalendar iCal = iCalendar.LoadFromFile(@"Calendars\Recurrence\RRULE1.ics");
            Program.TestCal(iCal);
            Event evt = iCal.Events[0];
            List<Occurrence> occurrences = evt.GetOccurrences(
                new iCalDateTime(2006, 1, 1, tzid, iCal),
                new iCalDateTime(2011, 1, 1, tzid, iCal));

            iCalDateTime dt = new iCalDateTime(2006, 1, 1, 8, 30, 0, tzid, iCal);
            int i = 0;

            while (dt.Year < 2011)
            {
                if ((dt > evt.Start) &&
                    (dt.Year % 2 == 1) && // Every-other year from 2005
                    (dt.Month == 1) &&
                    (dt.DayOfWeek == DayOfWeek.Sunday))
                {
                    iCalDateTime dt1 = dt.AddHours(1);
                    Assert.AreEqual(dt, occurrences[i].Period.StartTime, "Event should occur at " + dt);
                    Assert.AreEqual(dt1, occurrences[i + 1].Period.StartTime, "Event should occur at " + dt);
                    i += 2;
                }                

                dt = dt.AddDays(1);
            }
        }

 public Period(iCalDateTime start, TimeSpan duration)
     : this()
 {
     StartTime = start.Copy();
     if (duration != TimeSpan.MinValue)
     {
         Duration = new Duration(duration);
         EndTime = start + duration;
     }            
 }

        public override System.Collections.Generic.List<Period> Evaluate(iCalDateTime FromDate, iCalDateTime ToDate)
        {
            if (Start != null)
            {
                Period p = new Period(Start);
                if (!Periods.Contains(p))
                    Periods.Add(p);

                return base.Evaluate(FromDate, ToDate);
            }
            return new System.Collections.Generic.List<Period>();
        }

        public iCalDateTimeUTCSerializer(iCalDateTime dt)
            : base(dt)
        {
            // Make a copy of the iCalDateTime object, so we don't alter
            // the original
            DateTime = dt.Copy();

            // Set the iCalDateTime object to UTC time
            DateTime = DateTime.UTC;

            // Ensure time is serialized
            DateTime.HasTime = true;                    
        }

        public void TestAlarm(string Calendar, List<iCalDateTime> Dates, iCalDateTime Start, iCalDateTime End)
        {
            iCalendar iCal = iCalendar.LoadFromFile(@"Calendars\Alarm\" + Calendar);
            Program.TestCal(iCal);
            Event evt = iCal.Events[0];

            Start.iCalendar = iCal;
            Start.TZID = tzid;
            End.iCalendar = iCal;
            End.TZID = tzid;

            for (int i = 0; i < Dates.Count; i++)
            {
                Dates[i].TZID = tzid;
                Dates[i].iCalendar = iCal;
            }

            // Poll all alarms that occurred between Start and End
            List<AlarmOccurrence> alarms = evt.PollAlarms(Start, End);

            foreach (AlarmOccurrence alarm in alarms)
                Assert.IsTrue(Dates.Contains(alarm.DateTime), "Alarm triggers at " + alarm.Period.StartTime + ", but it should not.");
            Assert.IsTrue(Dates.Count == alarms.Count, "There were " + alarms.Count + " alarm occurrences; there should have been " + Dates.Count + ".");
        }

 public override List<Period> Evaluate(iCalDateTime FromDate, iCalDateTime ToDate)
 {
     List<Period> periods = base.Evaluate(FromDate, ToDate);
     // Add the initial specified date/time for the time zone entry
     periods.Insert(0, new Period(Start, null));
     return periods;
 }            

        public void RECURPARSE1()
        {
            iCalendar iCal = new iCalendar();

            Event evt = iCal.Create<Event>();
            evt.Summary = "Test event";
            evt.Start = new iCalDateTime(2006, 10, 1, 9, 0, 0);
            evt.Duration = new TimeSpan(1, 0, 0);
            evt.AddRecurrencePattern(new RecurrencePattern("Every 3rd month on the last tuesday and wednesday"));

            List<Occurrence> occurrences = evt.GetOccurrences(
                new iCalDateTime(2006, 10, 1), 
                new iCalDateTime(2007, 4, 30));

            iCalDateTime[] DateTimes = new iCalDateTime[]
            {
                new iCalDateTime(2006, 10, 1, 9, 0, 0),
                new iCalDateTime(2006, 10, 25, 9, 0, 0),
                new iCalDateTime(2006, 10, 31, 9, 0, 0),
                new iCalDateTime(2007, 1, 30, 9, 0, 0),
                new iCalDateTime(2007, 1, 31, 9, 0, 0),
                new iCalDateTime(2007, 4, 24, 9, 0, 0),
                new iCalDateTime(2007, 4, 25, 9, 0, 0)
            };

            for (int i = 0; i < DateTimes.Length; i++)
                Assert.AreEqual(DateTimes[i], occurrences[i].Period.StartTime, "Event should occur on " + DateTimes[i]);

            Assert.AreEqual(
                DateTimes.Length,
                occurrences.Count,
                "There should be exactly " + DateTimes.Length +
                " occurrences; there were " + occurrences.Count);
        }

 protected override void EvaluateExRule(iCalDateTime FromDate, iCalDateTime ToDate)
 {
 }

        protected List<iCalDateTime> CalculateChildOccurrences(iCalDateTime StartDate, iCalDateTime EndDate)
        {
            TimeCalculation TC = new TimeCalculation(StartDate, EndDate, this);                        
            switch (Frequency)
            {
                case FrequencyType.Yearly:
                    FillYearDays(TC);
                    FillByDay(TC);
                    FillMonths(TC);
                    break;
                case FrequencyType.Weekly: 
                    // Weeks can span across months, so we must
                    // fill months (Note: fixes RRULE10 eval)                    
                    FillMonths(TC);
                    break;
                case FrequencyType.Monthly:
                    FillDays(TC);
                    FillByDay(TC);
                    break;
                case FrequencyType.Daily:
                    FillHours(TC);
                    break;
                case FrequencyType.Hourly:
                    FillMinutes(TC);
                    break;
                case FrequencyType.Minutely:
                    FillSeconds(TC);
                    break;
                default:
                    throw new NotSupportedException("CalculateChildOccurrences() is not supported for a frequency of " + Frequency.ToString());                    
            }

            // Apply the BYSETPOS to the list of child occurrences
            // We do this before the dates are filtered by Start and End date
            // so that the BYSETPOS calculates correctly.
            // NOTE: fixes RRULE33 eval
            if (BySetPos.Count != 0)
            {
                List<iCalDateTime> newDateTimes = new List<iCalDateTime>();
                foreach (int pos in BySetPos)
                {
                    if (Math.Abs(pos) <= TC.DateTimes.Count)
                    {
                        if (pos > 0)
                            newDateTimes.Add(TC.DateTimes[pos - 1]);
                        else if (pos < 0)
                            newDateTimes.Add(TC.DateTimes[TC.DateTimes.Count + pos]);
                    }
                }

                TC.DateTimes = newDateTimes;
            }

            // Filter dates by Start and End date
            for (int i = TC.DateTimes.Count - 1; i >= 0; i--)
            {
                if ((iCalDateTime)TC.DateTimes[i] < StartDate ||
                    (iCalDateTime)TC.DateTimes[i] > EndDate)
                    TC.DateTimes.RemoveAt(i);
            }

            return TC.DateTimes;
        }

        /// <summary>
        /// Retrieves the iCalTimeZoneInfo object that contains information
        /// about the TimeZone, with the name of the current timezone,
        /// offset from UTC, etc.
        /// </summary>
        /// <param name="dt">The iCalDateTime object for which to retrieve the iCalTimeZoneInfo.</param>
        /// <returns>A TimeZoneInfo object for the specified iCalDateTime</returns>
        public iCalTimeZoneInfo GetTimeZoneInfo(iCalDateTime dt)
        {
            iCalTimeZoneInfo tzi = null;

            TimeSpan mostRecent = TimeSpan.MaxValue;
            foreach (iCalTimeZoneInfo curr in TimeZoneInfos)
            {
                DateTime Start = new DateTime(dt.Year - 1, 1, 1, 0, 0, 0, DateTimeKind.Utc);
                DateTime End = new DateTime(dt.Year + 1, 1, 1, 0, 0, 0, DateTimeKind.Utc);

                DateTime dtUTC = dt.Value;
                dtUTC = DateTime.SpecifyKind(dtUTC, DateTimeKind.Utc);

                // Time zones must include an effective start date/time.
                if (curr.Start == null)
                    continue;

                // Make a copy of the current start value
                iCalDateTime currStart = curr.Start.Copy();
                if (curr.TZOffsetTo != null)
                {
                    int mult = curr.TZOffsetTo.Positive ? -1 : 1;
                    dtUTC = dtUTC.AddHours(curr.TZOffsetTo.Hours * mult);
                    dtUTC = dtUTC.AddMinutes(curr.TZOffsetTo.Minutes * mult);
                    dtUTC = dtUTC.AddSeconds(curr.TZOffsetTo.Seconds * mult);
                    // Offset the current start value to match our offset time...
                    currStart = currStart.AddHours(curr.TZOffsetTo.Hours * mult);
                    currStart = currStart.AddMinutes(curr.TZOffsetTo.Minutes * mult);
                    currStart = currStart.AddSeconds(curr.TZOffsetTo.Seconds * mult);
                }

                // Determine the UTC occurrences of the Time Zone changes                
                if (curr.EvalStart == null ||
                    curr.EvalEnd == null ||
                    dtUTC < curr.EvalStart.Value ||
                    dtUTC > curr.EvalEnd.Value)
                    curr.Evaluate(Start, End);

                // If the date is past the last allowed date, then don't consider it!
                // NOTE: if this time zone ends as another begins, then there can
                // be up to a 1 year period of "unhandled" time unless we add a year
                // to the "Until" date.  For example, one time period "ends" in Oct. 2006
                // (the last occurrence), and the next begins in Apr. 2007.  If we didn't
                // add 1 year to the "Until" time, the 6 month period between Oct. 2006
                // and Apr. 2007 would be unhandled.

                // FIXME: this thinking may be flawed. We should try to find some other way...
                //
                //if (curr.Until != null &&
                //    dtUTC > curr.Until.AddYears(1))
                //    continue;

                foreach (Period p in curr.Periods)
                {
                    TimeSpan currentSpan = dtUTC - p.StartTime;
                    if (currentSpan.Ticks >= 0 &&
                        currentSpan.Ticks < mostRecent.Ticks)
                    {
                        mostRecent = currentSpan;
                        tzi = curr;
                    }
                }
            }

            return tzi;
        }

        protected List<iCalDateTime> GetOccurrences(iCalDateTime StartDate, iCalDateTime FromDate, iCalDateTime ToDate, int Count)
        {
            List<iCalDateTime> DateTimes = new List<iCalDateTime>();

            // If the Recur is restricted by COUNT, we need to evaluate just
            // after any static occurrences so it's correctly restricted to a
            // certain number. NOTE: fixes bug #13 and bug #16
            if (Count > 0)
            {
                FromDate = StartDate;
                foreach (iCalDateTime dt in StaticOccurrences)
                {
                    if (FromDate < dt)
                        FromDate = dt;
                }
            }

            // Handle "UNTIL" values that are date-only. If we didn't change values here, "UNTIL" would
            // exclude the day it specifies, instead of the inclusive behaviour it should exhibit.
            if (Until != null && !Until.HasTime)
                Until.Value = new DateTime(Until.Year, Until.Month, Until.Day, 23, 59, 59, Until.Value.Kind);

            // Ignore recurrences that occur outside our time frame we're looking at
            if ((Until != null && FromDate > Until) ||
                ToDate < StartDate)
                return DateTimes;

            // Narrow down our time range further to avoid over-processing
            if (Until != null && Until < ToDate)
                ToDate = Until;
            if (StartDate > FromDate)
                FromDate = StartDate;

            // If the interval is greater than 1, then we need to ensure that the StartDate occurs in one of the
            // "active" days/weeks/months/years/etc. to ensure that we properly "step" through the interval.
            // NOTE: Fixes bug #1741093 - WEEKLY frequency eval behaves strangely
            {
                long difference = DateUtils.DateDiff(Frequency, StartDate, FromDate, Wkst);
                while (difference % Interval > 0)
                {
                    FromDate = DateUtils.AddFrequency(Frequency, FromDate, -1);
                    difference--;
                }                
            }

            // If the start date has no time, then our "From" date should not either 
            // NOTE: Fixes bug #1876582 - All-day holidays are sometimes giving incorrect times
            if (!StartDate.HasTime)
            {
                FromDate = new iCalDateTime(FromDate.Year, FromDate.Month, FromDate.Day, StartDate.Hour, StartDate.Minute, StartDate.Second);
                FromDate.IsUniversalTime = StartDate.IsUniversalTime;
                FromDate.HasTime = false;
            }

            while (
                FromDate <= ToDate &&
                (
                    Count == int.MinValue ||
                    DateTimes.Count <= Count)
                )
            {
                // Retrieve occurrences that occur on our interval period
                if (BySetPos.Count == 0 && IsValidDate(FromDate) && !DateTimes.Contains(FromDate.Value))
                    DateTimes.Add(FromDate.Copy());

                // Retrieve "extra" occurrences that happen within our interval period
                if (Frequency > FrequencyType.Secondly)
                {
                    foreach (iCalDateTime dt in GetExtraOccurrences(FromDate, ToDate))
                    {
                        // Don't add duplicates
                        if (!DateTimes.Contains(dt))
                            DateTimes.Add(dt.Copy());
                    }
                }

                IncrementDate(ref FromDate);
            }

            return DateTimes;
        }

        public void IncrementDate(ref iCalDateTime dt, int Interval)
        {
            iCalDateTime old = dt.Copy();
            switch (Frequency)
            {
                case FrequencyType.Secondly: dt = old.AddSeconds(Interval); break;
                case FrequencyType.Minutely: dt = old.AddMinutes(Interval); break;
                case FrequencyType.Hourly: dt = old.AddHours(Interval); break;
                case FrequencyType.Daily: dt = old.AddDays(Interval); break;
                case FrequencyType.Weekly:
                    // How the week increments depends on the WKST indicated (defaults to Monday)
                    // So, basically, we determine the week of year using the necessary rules,
                    // and we increment the day until the week number matches our "goal" week number.
                    // So, if the current week number is 36, and our Interval is 2, then our goal
                    // week number is 38.
                    // NOTE: fixes RRULE12 eval.
                    int current = _Calendar.GetWeekOfYear(old.Value, System.Globalization.CalendarWeekRule.FirstFourDayWeek, Wkst),
                        lastLastYear = _Calendar.GetWeekOfYear(new DateTime(old.Year-1, 12, 31, 0, 0, 0, DateTimeKind.Local), System.Globalization.CalendarWeekRule.FirstFourDayWeek, Wkst),
                        last = _Calendar.GetWeekOfYear(new DateTime(old.Year, 12, 31, 0, 0, 0, DateTimeKind.Local), System.Globalization.CalendarWeekRule.FirstFourDayWeek, Wkst),
                        goal = current + Interval;

                    // If the goal week is greater than the last week of the year, wrap it!
                    if (goal > last)
                        goal = goal - last;
                    else if (goal <= 0)
                        goal = lastLastYear + goal;

                    int interval = Interval > 0 ? 1 : -1;
                    while (current != goal)
                    {
                        old = old.AddDays(interval);
                        current = _Calendar.GetWeekOfYear(old.Value, System.Globalization.CalendarWeekRule.FirstFourDayWeek, Wkst);
                    }

                    dt = old;
                    break;
                case FrequencyType.Monthly: dt = old.AddDays(-old.Day + 1).AddMonths(Interval); break;
                case FrequencyType.Yearly: dt = old.AddDays(-old.DayOfYear + 1).AddYears(Interval); break;
                default: throw new Exception("FrequencyType.NONE cannot be evaluated. Please specify a FrequencyType before evaluating the recurrence.");
            }
        }

            public TimeCalculation(iCalDateTime StartDate, iCalDateTime EndDate, RecurrencePattern Recur)
            {
                this.StartDate = StartDate;
                this.EndDate = EndDate;
                this.Recur = Recur;

                Year = StartDate.Value.Year;
                Month = StartDate.Value.Month;
                Day = StartDate.Value.Day;
                Hour = StartDate.Value.Hour;
                Minute = StartDate.Value.Minute;
                Second = StartDate.Value.Second;

                YearDays = new List<int>(Recur.ByYearDay);
                ByDays = new List<DaySpecifier>(Recur.ByDay);
                Months = new List<int>(Recur.ByMonth);
                Days = new List<int>(Recur.ByMonthDay);
                Hours = new List<int>(Recur.ByHour);
                Minutes = new List<int>(Recur.ByMinute);
                Seconds = new List<int>(Recur.BySecond);
                DateTimes = new List<iCalDateTime>();

                // Only check what months and days are possible for
                // the week's period of time we're evaluating
                // NOTE: fixes RRULE10 evaluation                
                if (Recur.Frequency == FrequencyType.Weekly)
                {                    
                    if (Months.Count == 0)
                    {
                        Months.Add(StartDate.Value.Month);
                        if (StartDate.Value.Month != EndDate.Value.Month)
                            Months.Add(EndDate.Value.Month);
                    }
                    if (Days.Count == 0)
                    {
                        DateTime dt = StartDate.Value;
                        while (dt < EndDate.Value)
                        {
                            Days.Add(dt.Day);
                            dt = dt.AddDays(1);
                        }
                        Days.Add(EndDate.Value.Day);
                    }
                }
                else
                {
                    if (Months.Count == 0) Months.AddRange(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 });                                
                    if (Days.Count == 0) Days.AddRange(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 });
                }
            }

 /// <summary>
 /// [Deprecated]: Use IsValidDate() instead.
 /// </summary>
 public bool CheckValidDate(iCalDateTime dt) { return IsValidDate(dt); }

        public void RRULE6()
        {
            iCalendar iCal = iCalendar.LoadFromFile(@"Calendars\Recurrence\RRULE6.ics");
            Program.TestCal(iCal);
            Event evt = iCal.Events[0];

            List<Occurrence> occurrences = evt.GetOccurrences(
                new iCalDateTime(1998, 1, 1, tzid, iCal), 
                new iCalDateTime(2000, 12, 31, tzid, iCal));

            iCalDateTime dt = new iCalDateTime(1998, 1, 1, 9, 0, 0, tzid, iCal);
            int i = 0;
            while (dt.Year < 2001)
            {
                if (dt >= evt.Start &&
                    dt.Month == 1 &&
                    dt <= new iCalDateTime(2000, 1, 31, 9, 0, 0, tzid, iCal))
                {
                    Assert.AreEqual(dt, occurrences[i].Period.StartTime, "Event should occur at " + dt);
                    i++;
                }

                dt = dt.AddDays(1);
            }
        }

        public void RECURPARSE6()
        {
            iCalendar iCal = new iCalendar();

            Event evt = iCal.Create<Event>();
            evt.Summary = "Test event";
            evt.Start = new iCalDateTime(2006, 1, 1, 9, 0, 0);
            evt.Duration = new TimeSpan(1, 0, 0);
            evt.AddRecurrencePattern(new RecurrencePattern("Every month on the first sunday, at 5:00PM, and at 7:00PM"));

            List<Occurrence> occurrences = evt.GetOccurrences(
                new iCalDateTime(2006, 1, 1), 
                new iCalDateTime(2006, 3, 31));

            iCalDateTime[] DateTimes = new iCalDateTime[]
            {
                new iCalDateTime(2006, 1, 1, 9, 0, 0),
                new iCalDateTime(2006, 1, 1, 17, 0, 0),
                new iCalDateTime(2006, 1, 1, 19, 0, 0),
                new iCalDateTime(2006, 2, 5, 17, 0, 0),
                new iCalDateTime(2006, 2, 5, 19, 0, 0),
                new iCalDateTime(2006, 3, 5, 17, 0, 0),
                new iCalDateTime(2006, 3, 5, 19, 0, 0)
            };

            for (int i = 0; i < DateTimes.Length; i++)
                Assert.AreEqual(DateTimes[i], occurrences[i].Period.StartTime, "Event should occur on " + DateTimes[i]);

            Assert.AreEqual(
                DateTimes.Length,
                occurrences.Count,
                "There should be exactly " + DateTimes.Length +
                " occurrences; there were " + occurrences.Count);
        }

        public void RECURPARSE5()
        {
            iCalendar iCal = new iCalendar();

            Event evt = iCal.Create<Event>();
            evt.Summary = "Test event";
            evt.Start = new iCalDateTime(2006, 1, 1, 9, 0, 0);
            evt.Duration = new TimeSpan(1, 0, 0);
            evt.AddRecurrencePattern(new RecurrencePattern("Every 10 minutes until 1/1/2006 9:50"));

            List<Occurrence> occurrences = evt.GetOccurrences(
                new iCalDateTime(2006, 1, 1), 
                new iCalDateTime(2006, 1, 31));

            iCalDateTime[] DateTimes = new iCalDateTime[]
            {
                new iCalDateTime(2006, 1, 1, 9, 0, 0),
                new iCalDateTime(2006, 1, 1, 9, 10, 0),
                new iCalDateTime(2006, 1, 1, 9, 20, 0),
                new iCalDateTime(2006, 1, 1, 9, 30, 0),
                new iCalDateTime(2006, 1, 1, 9, 40, 0),
                new iCalDateTime(2006, 1, 1, 9, 50, 0)
            };

            for (int i = 0; i < DateTimes.Length; i++)
                Assert.AreEqual(DateTimes[i], occurrences[i].Period.StartTime, "Event should occur on " + DateTimes[i]);

            Assert.AreEqual(
                DateTimes.Length,
                occurrences.Count,
                "There should be exactly " + DateTimes.Length +
                " occurrences; there were " + occurrences.Count);
        }

        /// <summary>
        /// Returns true if <paramref name="dt"/> is a date/time that aligns to (occurs within)
        /// the recurrence pattern of this Recur, false otherwise.
        /// </summary>
        public bool IsValidDate(iCalDateTime dt)
        {
            if (BySecond.Count != 0 && !BySecond.Contains(dt.Value.Second)) return false;
            if (ByMinute.Count != 0 && !ByMinute.Contains(dt.Value.Minute)) return false;
            if (ByHour.Count != 0 && !ByHour.Contains(dt.Value.Hour)) return false;
            if (ByDay.Count != 0)
            {
                bool found = false;
                foreach (DaySpecifier bd in ByDay)
                {
                    if (bd.CheckValidDate(this, dt))
                    {
                        found = true;
                        break;
                    }
                }
                if (!found)
                    return false;
            }
            if (ByWeekNo.Count != 0)
            {
                bool found = false;
                int lastWeekOfYear = _Calendar.GetWeekOfYear(new DateTime(dt.Value.Year, 12, 31), System.Globalization.CalendarWeekRule.FirstFourDayWeek, Wkst);
                int currWeekNo = _Calendar.GetWeekOfYear(dt.Value, System.Globalization.CalendarWeekRule.FirstFourDayWeek, Wkst);
                foreach (int WeekNo in ByWeekNo)
                {
                    if ((WeekNo > 0 && WeekNo == currWeekNo) ||
                        (WeekNo < 0 && lastWeekOfYear + WeekNo + 1 == currWeekNo))
                        found = true;
                }
                if (!found)
                    return false;
            }
            if (ByMonth.Count != 0 && !ByMonth.Contains(dt.Value.Month)) return false;
            if (ByMonthDay.Count != 0)
            {
                // Handle negative days of month (count backwards from the end)
                // NOTE: fixes RRULE18 eval
                bool found = false;
                int DaysInMonth = _Calendar.GetDaysInMonth(dt.Value.Year, dt.Value.Month);
                foreach (int Day in ByMonthDay)
                {
                    if ((Day > 0) && (Day == dt.Value.Day))
                        found = true;
                    else if ((Day < 0) && (DaysInMonth + Day + 1 == dt.Value.Day))
                        found = true;
                }

                if (!found)
                    return false;
            }
            if (ByYearDay.Count != 0)
            {
                // Handle negative days of year (count backwards from the end)
                // NOTE: fixes RRULE25 eval
                bool found = false;
                int DaysInYear = _Calendar.GetDaysInYear(dt.Value.Year);
                DateTime baseDate = new DateTime(dt.Value.Year, 1, 1);

                foreach (int Day in ByYearDay)
                {
                    if (Day > 0 && dt.Value.Date == baseDate.AddDays(Day - 1))
                        found = true;
                    else if (Day < 0 && dt.Value.Date == baseDate.AddYears(1).AddDays(Day))
                        found = true;
                }
                if (!found)
                    return false;
            }
            return true;
        }

        public void RRULE13()
        {
            iCalendar iCal = iCalendar.LoadFromFile(@"Calendars\Recurrence\RRULE13.ics");
            Program.TestCal(iCal);
            Event evt = iCal.Events[0];

            List<Occurrence> occurrences = evt.GetOccurrences(
                new iCalDateTime(1996, 1, 1, tzid, iCal), 
                new iCalDateTime(1999, 1, 1, tzid, iCal));

            iCalDateTime[] DateTimes = new iCalDateTime[]
            {
                new iCalDateTime(1997, 9, 2, 9, 0, 0, tzid, iCal),
                new iCalDateTime(1997, 9, 4, 9, 0, 0, tzid, iCal),
                new iCalDateTime(1997, 9, 16, 9, 0, 0, tzid, iCal),
                new iCalDateTime(1997, 9, 18, 9, 0, 0, tzid, iCal),
                new iCalDateTime(1997, 9, 30, 9, 0, 0, tzid, iCal),
                new iCalDateTime(1997, 10, 2, 9, 0, 0, tzid, iCal),
                new iCalDateTime(1997, 10, 14, 9, 0, 0, tzid, iCal),
                new iCalDateTime(1997, 10, 16, 9, 0, 0, tzid, iCal)
            };

            for (int i = 0; i < DateTimes.Length; i++)
                Assert.AreEqual(DateTimes[i], occurrences[i].Period.StartTime, "Event should occur on " + DateTimes[i]);

            Assert.AreEqual(
                DateTimes.Length,
                occurrences.Count,
                "There should be exactly " + DateTimes.Length + " occurrences; there were " + occurrences.Count);
        }

 protected void EnsureByXXXValues(iCalDateTime StartDate)
 {
     // If the frequency is weekly, and
     // no day of week is specified, use
     // the original date's day of week.
     // NOTE: fixes RRULE7 and RRULE8 handling
     if (Frequency == FrequencyType.Weekly &&
         ByDay.Count == 0)
         this.ByDay.Add(new DaySpecifier(StartDate.Value.DayOfWeek));            
     if (Frequency > FrequencyType.Secondly &&
         this.BySecond.Count == 0 &&
         StartDate.HasTime /* NOTE: Fixes a bug where all-day events have BySecond/ByMinute/ByHour added incorrectly */)
         this.BySecond.Add(StartDate.Value.Second);
     if (Frequency > FrequencyType.Minutely &&
         this.ByMinute.Count == 0 &&
         StartDate.HasTime /* NOTE: Fixes a bug where all-day events have BySecond/ByMinute/ByHour added incorrectly */)
         this.ByMinute.Add(StartDate.Value.Minute);
     if (Frequency > FrequencyType.Hourly &&                
         this.ByHour.Count == 0 &&
         StartDate.HasTime /* NOTE: Fixes a bug where all-day events have BySecond/ByMinute/ByHour added incorrectly */)
         this.ByHour.Add(StartDate.Value.Hour);
     // If neither BYDAY, BYMONTHDAY, or BYYEARDAY is specified,
     // default to the current day of month
     // NOTE: fixes RRULE23 handling, added BYYEARDAY exclusion
     // to fix RRULE25 handling
     if (Frequency > FrequencyType.Weekly &&
         this.ByMonthDay.Count == 0 && 
         this.ByYearDay.Count == 0 && 
         this.ByDay.Count == 0) 
         this.ByMonthDay.Add(StartDate.Value.Day);
     // If neither BYMONTH nor BYYEARDAY is specified, default to
     // the current month
     // NOTE: fixes RRULE25 handling
     if (Frequency > FrequencyType.Monthly &&
         this.ByYearDay.Count == 0 && 
         this.ByDay.Count == 0 &&
         this.ByMonth.Count == 0)
         this.ByMonth.Add(StartDate.Value.Month);
 }