@node tzset
@subsection @code{tzset}
@findex tzset

POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9799919799/functions/tzset.html}

Gnulib module: tzset
@mindex tzset

Portability problems fixed by Gnulib:
@itemize
@item
On native Windows platforms (mingw, MSVC), this function works incorrectly
when the environment variable @env{TZ} has been set by Cygwin.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@item
@c https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/tzset
Native Windows platforms (mingw, MSVC) support only a subset of
POSIX-specified values for the @env{TZ} environment variable,
consisting of a time zone abbreviation containing exactly three ASCII
letters with no daylight saving time or angle brackets, and with no
support for @code{tz} database settings like
@code{TZ='America/New_York'}.  Even this subset does not work on
applications built via the Universal Windows Platform, as it does not
make environment variables like @env{TZ} available to applications.
@item
Older POSIX platforms do not support angle brackets in @env{TZ} values,
as this feature was added in IEEE Std 1003.1-2001.
@end itemize
