Hi Paul. Good question. I had to dig around a bit but here's what I found. timex may read TZif files in trying to determine the local timezone of the machine. However, it also has a dependency on the tzdata library for its Tzdata.TimeZoneDatabase and a few other methods (such as checking whether specified timezones exist). Unless configured otherwise, the tzdata library will check on start up and then once a day whether https://data.iana.org/time-zones/tzdata-latest.tar.gz is different from its local copy of the TZ data. If it is, then it builds a new internal representation of the data; it is this operation that requires parsing the rules, etc.. All that being said, a new version of tzdata (1.1.2) was just released that updates the tz data bundled with the library to 2024b AND fixes the parsing of the months to accept "April", "February", etc..