bool IsInDSTForYear (AdjustmentRule rule, DateTime dateTime, int year)
{
DateTime DST_start = TransitionPoint (rule.DaylightTransitionStart, year);
DateTime DST_end = TransitionPoint (rule.DaylightTransitionEnd, year + ((rule.DaylightTransitionStart.Month < rule.DaylightTransitionEnd.Month) ? 0 : 1));
if (dateTime.Kind == DateTimeKind.Utc) {
DST_start -= BaseUtcOffset;
DST_end -= (BaseUtcOffset + rule.DaylightDelta);
}
return (dateTime >= DST_start && dateTime < DST_end);
}