From Pocket Mobility:
ShiftCal is a program that allows you to put your shift calendar into your Palm Date Book. All you need to do is provide a little information about your shift schedule, and ShiftCal will do the rest. The shift calendar data appears in your Date Book alongside any other appointments you have created. You can choose to display just one shift or your choice of multiple shifts. You may change or delete your calendar at any time without affecting the rest of your appointments. The shift calendar is accurate to the year 2040, which is the current limit of the Palm Date Book.