By the gnu date imput secifications, if the input year is less than 68, 2000 is added to it, so to start out the year is 2000. The month range is 1-12 for Jan-Dec, so "00" gives you the previous Dec (1999). And the range for days is 1-31, so "00" gives you the last day of the previous month. Therefore, "1999-11-30".
