These cases cover the examples of EDTF level 1 dates, datetimes, and time intervals given at https://www.loc.gov/standards/datetime/.
Level 1 requires support for Level 0 as well as the following features:
Extended year (see rules)
Season (see rules)
Qualification of date (see rules)
- qualified calendar date
- qualified reduced precision date (year and month only)
- qualified reduced precision date (year only)
Unspecified digit(s) (see rules)
- calendar date with unspecified digits
- reduced precision date (year and month only) with unspecified digits
- reduced precision date (year only) with unspecified digits
Time interval (see rules)
The following intervals also use the qualification rules: