EDTF Dates

Created by Glen Barnes, Modified on Wed, 31 Jan 2024 at 07:17 AM by Glen Barnes

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?


  1. Dates are formatted as YYYY-MM-DD
  2. You may have partial dates YYYY or YYYY-MM
  3. You may have a date that is an interval. YYYY-MM-DD/YYYY-MM-DD
  4. You can specify decades YYYx
  5. You can specify centuries YYxx
  6. You may have Uncertain and/or Approximate dates:
    1. Uncertain: Possibly the year 1984, but not definitely YYYY?
    2. Approximate: Approximately the year 1984 YYYY~
  7. You can combine different settings
  8. For a date where we are completely uncertain, we can use uuuu


  • 25th March 1941: 1941-03-25
  • February 2006: 2006-02
  • 1945: 1945
  • Between 2000 and 2005: 2000-2005
  • Between Jan 1980 and 2005: 1980/2005-01
  • The 1970’s: 197x
  • The 18th Century: 18xx
  • Possibly 1984: 1984?
  • Approximately 1984: 1984~
  • Approximately the 1960’s: 1960-1969~
  • We have no idea what date it is: uuuu

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