Holding cyclic or recurrence information must be pretty common. An example of it would be the appointment recurrence dialog in Outlook.
I just wondered if there already exists a common or standard data structure for holding the details, rather than my trying to work through it from first principles.
Following the Outlook model, the following might be applicable, but I haven't suggested any data types:
pattern_cycle (daily, weekly, monthly, yearly)
pattern_recurrence (e.g. recur every 2 weeks)
pattern_day (m t w t f s s)