Specify calendrical units.
| Era | Specifies the era unit. |
| Year | Specifies the year unit. |
| Month | Specifies the month unit. |
| Day | Specifies the day unit. |
| Hour | Specifies the hour unit. |
| Minute | Specifies the minute unit. |
| Second | Specifies the second unit. |
| Week | Specifies the week unit. |
| Weekday | Specifies the weekday unit. |
| WeekdayOrdinal | Specifies the ordinal weekday unit. |
| Quarter | Specifies the quarter of the calendar. |