| Level 0 | ||
|---|---|---|
| Feature | Implementation Status | |
| Loose | Strict | |
| Date | done | unstarted |
| Date & Time | unstarted | unstarted |
| Time Interval | unstarted | unstarted |
| Level 1 | ||
| Feature | Implementation Status | |
| Loose | Strict | |
| Letter-prefixed Calendar Year | done | unstarted |
| Seasons | done | unstarted |
| Qualification Of a Date (Complete) | unstarted | unstarted |
| Unspecified Digit(s) From The Right | unstarted | unstarted |
| Extended Interval | unstarted | unstarted |
| Negative Calendar Year | done | unstarted |
| Level 2 | ||
| Feature | Implementation Status | |
| Loose | Strict | |
| Exponential Year | done | unstarted |
| Significant Digits | partial | unstarted |
| Sub-year Groupings | done | unstarted |
| Set Representation | unstarted | unstarted |
| Qualification | unstarted | unstarted |
| Unspecified Digit | unstarted | unstarted |
| Approximate, Uncertain, or Unspecified Interval | unstarted | unstarted |