Abstract: A series of recurring events is represented using a computer system that includes a processor and a storage medium readable by the processor. The series is represented by storing on the storage medium a pattern that represents dates on which events in the series of recurring events occur. The pattern includes a first entry that may identify days of a week on which an event in the series of recurring events may occur, a second entry that may provide a measure of a number of days between events in the series of recurring events, and a third entry that may provide a measure of a number of months between events in the series of recurring events. Indicators that indicate whether each of the first, second or third entries are to be considered in extracting occurrences of the series of recurring events from the pattern are also stored on the storage medium. The indicators may be stored within the entries.