Cyclic periods

Examples of cyclic periods are a day, a week, and a fortnight, with fixed intervals of 1 day, 7 days, and 14 days, respectively. An academic semester cannot be described as a cyclic period, because spring, summer, and fall semesters have different lengths.

This example shows a lunar calendar month, assumed to be 28 days:

Cyclic period: work days and free days

 PERIOD NAME     = MOON
 PERIOD TYPE     = A
 INTERVAL ORIGIN = 7 February 2003 (date of a new moon)
 INTERVAL        = 28 days

This example shows a period that is useful if you need to take a backup every 4 work days:

Cyclic period: work days only

 PERIOD NAME     = BACKUP
 PERIOD TYPE     = W
 INTERVAL ORIGIN = 2 January 2003
 INTERVAL        = 4 work days