Hi Jon,

I'm using the latest version of the moment-timezone library which claims to be using the 2023c version of the tzdb. When I look through the source code, there's a JSON file which seems to have the timezone definitions. Here's what I see for Mexico City for example. It looks like CDT is in there.
When I use this library and try to simulate Mexico City in my browser it displays CDT where I expect to see CST.

"America/Mexico_City|LMT MST CST MDT CDT CWT|6A.A 70 60 60 50 50|012131242425242424242424242424242424242424242424242424242424242424242|-1UQF0 deL0 8lc0 17c0 10M0 1dd0 gEn0 TX0 3xd0 Jb0 6zB0 SL0 e5d0 17b0 1Pff0 1lb0 14p0 1lb0 14p0 1lb0 14p0 1nX0 11B0 1nX0 1fB0 WL0 1fB0 1lb0 14p0 1lb0 14p0 1nX0 11B0 1nX0 11B0 1nX0 11B0 1nX0 14p0 1lb0 14p0 1lb0 14p0 1nX0 11B0 1nX0 11B0 1nX0 14p0 1lb0 14p0 1lb0 14p0 1lb0 14p0 1nX0 11B0 1nX0 11B0 1nX0 14p0 1lb0 14p0 1lb0 14p0 1nX0 11B0 1nX0|20e6",

On Mon, Apr 10, 2023 at 09:41 Jon Skeet <skeet@pobox.com> wrote:

Could you clarify which specific time zone you're seeing an issue with, which version of TZDB you're using, and what tool you're using?
For example, from https://nodatime.org/tzvalidate/generate?version=2023c, both "Mexico/General" and "America/Mexico_City" are in CST (from October 2022 onwards). "Mexico/BajaNorte" is still alternating between PST and PDT. "Mexico/BajaSur" is now in MST (from October 2022 onwards).

On Mon, 10 Apr 2023 at 17:25, Var Nazari via tz <tz@iana.org> wrote:
Hello,

Mexico has recently abolished daylight savings except for where they border with the United States. I believe the timezone database is now inaccurate because it should not be showing CDT for most of the country any longer and should be CST instead. It seems like this was addressed in release notes for the tzdb version 2022f and 2022g but I'm not sure that the correct changes were applied. Could you verify/explain why the timezones in Mexico are still recorded as CDT? Is this a mistake?

Thank you