A calendar application for use with a first portable electronic device includes time-dependent events having a start time and an end time and proximity-dependent events having a specified device ID that corresponds to a second portable electronic device. Both the time-dependent events and the proximity-dependent events are stored in the calendar application and the proximity-dependent event is convertible into a time-dependent event. A proximity reminder is generated when the second portable electronic device is in short range radio frequency communication range of the first portable electronic device.