public string GenerateOldWhen() { ExDateTime?valueAsNullable = base.GetValueAsNullable <ExDateTime>(InternalSchema.OldStartWhole); ExDateTime?valueAsNullable2 = base.GetValueAsNullable <ExDateTime>(InternalSchema.OldEndWhole); return(CalendarItem.GenerateWhenForSingleInstance(valueAsNullable, valueAsNullable2).ToString(base.Session.InternalPreferedCulture)); }