TIMEZONE(3) Library Functions Manual TIMEZONE(3)

timezone
return the timezone abbreviation

Standard C Library (libc, -lc)

char *
timezone(int zone, int dst);

This interface is available for compatibility only and will disappear in a future software release; it is impossible to reliably map timezone's arguments to a time zone abbreviation. See ctime(3); see tzset(3) for the new definition of this interface.

The timezone() function returns a pointer to a time zone abbreviation for the specified zone and dst values. Zone is the number of minutes west of GMT and dst is non-zero if daylight savings time is in effect.

ctime(3), tzset(3)

A timezone() function appeared in Version 7 AT&T UNIX.
April 19, 1994 NetBSD 9.0