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));
}