Date uncertainty

Uncertainty, approximation, and missing precision are different problems. You may know that an event happened in a particular year but not its month; you may suspect a year without being sure; or a source may intentionally give an approximate period. Do not flatten these into one exact-looking date. Use plain language that preserves the distinction, such as month unknown, probably 2004, or approximately 2004. The EDTF specification provides structured representations for these cases, but applications differ in what they accept. Keep a human-readable note even when using a machine-readable convention. Explain the evidence behind a range and avoid implying that every point within it is equally likely unless that is justified. Uncertainty is useful metadata: it identifies what a future discovery could improve without making the existing record unusable.

Editorial review: 2026-09-23. New evidence may change this account.

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