the code and data maintained as part of the IANA Time Zone Database.
The IANA asserts that the database is in the public domain.

For more information, see
https://www.iana.org/time-zones
ftp://ftp.iana.org/tz/code/tz-link.html
https://datatracker.ietf.org/doc/html/rfc6557

rm -rf work
mkdir work
go build -o work/mkzip mkzip.go # build now for correct paths in build errors
cd work
mkdir zoneinfo
curl -sS -L -O https://www.iana.org/time-zones/repository/releases/tzcode$CODE.tar.gz
curl -sS -L -O https://www.iana.org/time-zones/repository/releases/tzdata$DATA.tar.gz
tar xzf tzcode$CODE.tar.gz
tar xzf tzdata$DATA.tar.gz

if ! make CFLAGS=-DSTD_INSPIRED AWK=awk TZDIR=zoneinfo posix_only >make.out 2>&1; then