Partial dates for publications: year, year and month, or full date

Many publications are not dated to the day: for a monograph you often know only the year, for a journal the year and month. The date field, however, used to insist on day, month and year.

Librarians had to put an arbitrary “01.01.” (1 January) in front of the year, which skewed filter, sorting and export results and showed up in BibTeX and EndNote as an exact date.

Publication dates are now stored in the EDTF format, so 2024, 2024-03 and 2024-03-15 are all valid. Filters, the facets in the sidebar, the BibTeX, EndNote and Atom exports and the API all work with the precision that was actually entered.

EDTF stands for Extended Date/Time Format, an open standard from the Library of Congress for structured dates of varying precision.