README.md

EDTF level 2

These cases cover the examples of EDTF level 2 dates, datetimes, and time intervals given at https://www.loc.gov/standards/datetime/.

Level 2 requires support for Level 1 as well as the following features:

Extended year (see rules)

• exponential year
• year with significant digits

Year subdivision (see rules)

• season
• quarter
• quadrimester
• semestral

Qualification of date (see rules)

• qualified date component(s)
• qualified date component group(s)

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

Range of possible dates (see rules)

• on or before date
• on or after date
• no earlier than date A and no later than date B

Time interval (see rules)

The following intervals also use the unspecified digit rules:

• with unspecified digits in start
• with unspecified digits in end
• with unspecified digits in start and end

The following intervals also use the qualification rules:

• with qualified start
• with qualified end
• with qualified start and end

Under construction:

• with start on or before date
• with end on or after date

Set of dates (see rules)

Under construction