This INTEGER is the average temperature, in degrees Celsius, that the rear-of-module exhaust sensor recorded over the statistics-collection interval. Because a hot rear-zone reading paired with normal fan speeds elsewhere often points to the chassis's exhaust path itself being blocked, for example by cabling stacked too close to the rear of the rack, an admin diagnosing a SIOC cooling problem checks this specific zone rather than relying only on the SIOC's single roll-up thermal status flag. An average holding near 50 across the interval is normal for this zone; a rising average even while individual max readings stay in range would flag a slow thermal drift worth watching.