CCTZ contains two libraries that cooperate with <chrono> to give
C++ programmers all the necessary tools for computing with dates,
times, and time zones in a simple and correct manner. The libraries
in CCTZ are:

_ The Civil-Time Library - This is a header-only library that
  supports computing with human-scale time, such as dates (which
  are represented by the cctz::civil_day class). This library is
  declared in civil_time.h.

_ The Time-Zone Library - This library uses the IANA time zone
  database that is installed on the system to convert between
  _absolute time_ and _civil time_. This library is declared in
  time_zone.h.

WWW: https://github.com/google/cctz