Hello!

We will soon deploy some fixes for date parsing that especially affect Czech and possibly other languages as well.

Wikidata’s parsing of dates in the Czech language has long been affected by some issues (T221097), where some reasonable representations couldn’t be parsed (e.g. 01.02.2023), while others were parsed incorrectly: for example, 11.12.2023 (11 December 2023) was parsed as 12 November 2023, and 07.05.1997 (7 May 1997) bizarrely became 30 June 1997.

Matěj Suchánek has investigated these errors and implemented a solution, which will be deployed on February 15. As far as we can tell, all the changes it produces are positive: that is, if the way a date is parsed changes, then the old behavior was bad, and the change is an improvement. Nevertheless, it’s possible that some users expected the old behavior, or that some external programs might even be broken by the change. Users who add time data to Wikidata should make sure that the date shown to them as a result of their edit is correct. If you want to test the behavior changes, the new code is already live on Beta Wikidata.

We are currently looking into other languages that may be affected as well.

If you have any questions or want to provide feedback please leave us a comment on this ticket.

Cheers,