[1] Man page of GETTIMEOFDAY () https://linuxjm.osdn.jp/html/LDP_man-pages/man2/gettimeofday.2.html
[2] [tz] Java & Rearguard () https://mm.icann.org/pipermail/tz/2019-June/028048.html
[3] [tz] Java & Rearguard () https://mm.icann.org/pipermail/tz/2019-June/028049.html
[4] [tz] Java & Rearguard () https://mm.icann.org/pipermail/tz/2019-June/028052.html