rem: get previous() { if (this.item.recurrenceInfo) return this.item.recurrenceInfo.getPreviousOccurrence(this.item, aStartDate); return null; } 
add: get icalString() { throw Components.results.NS_NOT_IMPLEMENTED; }, 
context:     get previous() {        if (this.item.recurrenceInfo)            return this.item.recurrenceInfo.getPreviousOccurrence(this.item, aStartDate);        return null;    }
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/b4a3b00ed58fa70e21c7fdade2185d7787d28428/calItemBase.js/clean/calendar/base/src/calItemBase.js