Many dates that you may want to record may be ‘fuzzy’ dates, that is they may be uncertain or approximate. For example dates such as “Circa 1953” or “1940s?”. To handle these dates you can enter dates in EDTF format. So what are some rules and examples of use?
What is EDTF?
EDTF (Extended Date/Time Format) is a standardized date format designed to represent precise, uncertain, approximate, and complex dates in a structured way. It is an extension of ISO 8601, developed by the Library of Congress to improve handling of historical, archival, and bibliographic data.
Why does STQRY use EDTF and what are the benefits of EDTF?
Many dates that you may want to record may be ‘fuzzy’ dates, that is they may be uncertain or approximate. For example dates such as “Circa 1953” or “1940s?”.
With EDTF dates you can record any date, even if you're unsure of its accuracy or the date is a range of dates.
| Rule | Description | Example |
| Full Date | Year, month, and day in YYYY-MM-DD format | 1941-03-25 |
| Partial Date (Month & Year) | Year and month only in YYYY-MM format | 2006-02 |
| Year Only | Just the year in YYYY format | 1945 |
| Date Interval | A range between two dates, formatted as YYYY-MM-DD/YYYY-MM-DD | 1980/2005-01 |
| Decades | Uses YYYx format to represent a decade | 197x |
| Centuries | Uses YYxx format to represent a century | 18xx |
| Uncertain Date | If the date is uncertain, add a "?" | 1984? |
| Approximate Date | If the date is approximate, add a "~" | 1984~ |
| Approximate Decade | A rough estimate of a decade range | 1960-1969~ |
| Completely Uncertain Date | If the date is entirely unknown, use "uuuu" | uuuu |
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