And there is also TAI (Pure Earth Atomic Time), and GPST (GPS Time), Galileo Time (GST), BeiDou Time (BDT) — all strongly monotonic sequences of atomic seconds

And there is also TAI (Pure Earth Atomic Time), and GPST (GPS Time), Galileo Time (GST), BeiDou Time (BDT) — all strongly monotonic sequences of atomic seconds with different frozen offsets. All using weighted averages of different atomic clocks somewhere. Fascinating.