Examples of Interval Specifications

Date Intervals, Formats, and Functions

Table 3.1 shows examples of different kinds of interval specifications.

Name	Kind of Interval
YEAR	years starting in January
YEAR.10	fiscal years starting in October
YEAR2.7	biennial intervals starting in July of even years
YEAR2.19	biennial intervals starting in July of odd years
YEAR4.11	four-year intervals starting in November of leap years (frequency of U.S. presidential elections)
YEAR4.35	four-year intervals starting in November of even years between leap years (frequency of U.S. midterm elections)
WEEK	weekly intervals starting on Sundays
WEEK2	biweekly intervals starting on first Sundays
WEEK1.1	same as WEEK
WEEK.2	weekly intervals starting on Mondays
WEEK6.3	six-week intervals starting on first Tuesdays
WEEK6.11	six-week intervals starting on second Wednesdays
WEEKDAY	daily with Friday-Saturday-Sunday counted as the same day (five-day work week with a Saturday-Sunday weekend)
WEEKDAY17W	same as WEEKDAY
WEEKDAY67W	daily with Thursday-Friday-Saturday counted as the same day (five-day work week with a Friday-Saturday weekend)
WEEKDAY1W	daily with Saturday-Sunday counted as the same day (six-day work week with a Sunday weekend)
WEEKDAY3.2	three-weekday intervals (with Friday-Saturday-Sunday counted as one weekday) with the cycle three-weekday periods aligned to Monday 4 Jan 1960
HOUR8.7	eight-hour intervals starting at 6 a.m., 2 p.m., and 10 p.m. (might be used for work shifts)