As you might be aware, I maintain the date time support in PHP. As part 
of that I regularly have to update the rules that timezones employ - 
changes in Daylight Saving Time rules, or other changes to rules due to 
political foibles. 

In the last few years, the maintainer of the Iana TZ Data project has 
diverged somewhat from the consensus of the community, and degraded some 
data by no longer having an entry for each country and merged timezones 
where data does not differ since 1970. (Removing transitions from these 
regions where data **does** differ before 1970, even if these were 

Java's date/time maintainer has created a fork based on the original 
Iana TZ data to put back some of the removed/deprecated data to better 
serve their users, and I would think that this is also best suited as a 
data set for PHP.

If you want to read about the intricacies, see: 

But this does mean a divergence from the "official" TZ data, although 
Joda's data is arguably better. My recommendation is that from the 2022b 
release we switch to Joda's version. (I will today merge in the 2022a 
data from the Iana source.)


If you want to discuss this live, come find me in "Room 11": 

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