Alas, while the current tz package can get the day-skipping part of the Julian-to-Gregorian calendar transition right, it gets pre-transition weekdays worng. (Getting them right would require special casing for big offsets from standard time in localtime.c) @dashdashado Script started on Sat, Nov 10, 2018 6:47:15 PM $ cat fake Zone America/Somewhere -268:56:02 - LMT 1752 Sep 3 -4:56:02 - LMT $ ./zic fake $ ./zdump -v America/Somewhere America/Somewhere -9223372036854775808 = NULL America/Somewhere -9223372036854689408 = NULL America/Somewhere Thu Sep 14 04:56:01 1752 UT = Sat Sep 2 23:59:59 1752 LMT isdst=0 gmtoff=-968162 America/Somewhere Thu Sep 14 04:56:02 1752 UT = Thu Sep 14 00:00:00 1752 LMT isdst=0 gmtoff=-17762 America/Somewhere 9223372036854689407 = NULL America/Somewhere 9223372036854775807 = NULL $ exit exit Script done on Sat, Nov 10, 2018 6:47:36 PM