This object reports the highest temperature this specific sensor has recorded since the module was last rebooted, as the description states, meaning it only resets on a reboot rather than tracking a rolling window. This makes it valuable for retroactively confirming whether a card experienced a thermal excursion -- say, during an HVAC outage overnight -- even after the live reading has long since returned to normal and would otherwise show nothing unusual. For example, a high-water mark of 81 degrees C recorded overnight, even though the current reading is back down to 45, reveals a past cooling problem that a live-only reading would have completely missed.