This Counter32 is a free-running, cumulative tally of PCIe ERR_FATAL messages recorded against this PCIe endpoint's receive path since the counter was last reset by a reboot or reseat; concretely, the link partner signalled an unrecoverable (fatal) PCIe error condition over the ERR_FATAL sideband message. Because it never wraps back to zero on its own, an admin uses it as the lifetime baseline against which the 15-minute/hourly/daily/weekly gauges on this same row are compared to spot fresh activity. A blade that shipped with this counter at 0 and now reads 187 has accumulated 187 such faults since it was last powered up, which on a healthy riser should stay at 0.