Description of calendar_start_end

    {  CALENDAR_YEAR_START_DATE |
	CALENDAR_YEAR_END_DATE |
	CALENDAR_QUARTER_START_DATE |
	CALENDAR_QUARTER_END_DATE |
	CALENDAR_MONTH_START_DATE |
	CALENDAR_MONTH_END_DATE |
	CALENDAR_WEEK_START_DATE |
	CALENDAR_WEEK_END_DATE
    }( dtexpr [ , nlsparam ] )