On 2023-12-06, Max Nikulin <maniku...@gmail.com> wrote: > > My reading of this document is that EST5EDT file in tzdata is a POSIX > extension, not "true" POSIX. >
POSIX format specification The POSIX time zone format is the traditionally used format for AIX systems and provides a slight performance advantage over the Olson time zone format. Example of a POSIX format is EST5EDT. The advantage of POSIX is that you can easily and explicitly specify the time zone and daylight saving time (DST) details manually, however you wish. The performance of applications that call time functions will be faster than using Olson specification. And whenever a nation's government decides to change its DST rules, the POSIX format is simpler because we can simply change the variable definition. There is no need to install any new patch to update time database files, as Olson requires. Does this apply to "us?" https://developer.ibm.com/articles/au-aix-posix/