It is an enumerated type used as the return type for member date_order, that may take any of the following member enum values:
| value | date order |
|---|---|
| no_order | No specific order, or format contains variable components other than day, month and year. |
| dmy | day, month, year |
| mdy | month, day, year |
| ymd | year, month, day |
| ydm | year, day, month |