This is a library that implements rules for recurring events. These are the types of recurrence that the library implements: 1) Days-based recurrence - events that happen once each some days. E.g.: * each other day. * once each five days. * once each two weeks. 2) Months-based recurrence - events that happen once each some months. 2.1) Day-of-month-based - events that happen in the same day of month. E.g.: * every month on 1st. * each other month on 15th. * yearly, on 24th. It is possible to define the day relative to the end of the month. E.g.: * each other month on the last day. * each three months, on the 10th day to the end. 2.2) Day-of-week-based - events that happen in some day-of-week. E.g.: * every month on the second Tuesday. * each other month on the fourth Wednesday. It is possible to define the day relative to the end of the month. E.g.: * each month, on the last Saturday. * each four months, on the second to last Sunday. The rules need an anchor to be applied to. The anchor defines the first date or period that will generate the first occurrence. This first occurrence has an number zero, the following one has number one, and so on. Negative numbers are also possible for occurrences before the anchor.