This repository mirrors the data fetched from https://data.iana.org/time-zones/releases/ . It started based on https://data.iana.org/time-zones/releases/tzdata2021a.tar.gz.
Additional for windows https://raw.githubusercontent.com/unicode-org/cldr/master/common/supplemental/windowsZones.xml was added to tzdata folder like described in https://howardhinnant.github.io/date/tz.html#Installation (section "Windows specific").
To keep the database up to date just download the latest version of tzdata and untar it into the tzdata folder (same for windowsZones.xml).
The CMakeLists.txt file created by Barco provides an easy mechanism to integrate this lib into BasicToolBox. It is actually an indirect dependency introduced by Howard Hinnant's libdate. The original CMakeList.txt file libdate was adapted to explicitely express a dependency to tzdata.
For more details have a look into this CMakeLists.txt and the one in libdate (https://github.com/barcoopensource/date/blob/master/CMakeLists.txt#L39).