An occasion database and a date converter are provided in a device which allows a user to retrieve restored occasion information, whether the occasion occurs in the Gregorian calendar or a non-Gregorian calendar. A formula is stored for each occasion to allow its date to be calculated for any given year....http://www.google.de/patents/US6108640?utm_source=gb-gplus-sharePatent US6108640 - System for calculating occasion dates and converting between different calendar systems, and intelligent agent for using same
