On 9/29/22 11:25, Michael H Deckers wrote:
the (incorrect) offset of -06:40:00 h presently used for local mean time at Matamoros.
Thanks for reporting that bug. It should be -06:30:00; apparently I transcribed the number incorrectly from Shanks & Pottenger. While reviewing this I noticed another bug: the 1922 transition in Tijuana was off by an hour due to my mistake in subtracting timestamps. The first attached patch fixes both of these problems. For a transition out of LMT to a whole-number standard time, it's better to use UT for the transition time, so I installed the second attached patch to do this more systematically in US timestamps (also, one transition in Spanish Morocco). This second patch doesn't affect the generated timestamps.