This field is part of the PCIeFatalStats table's tally of ACS (Access Control Services) violation errors on this compute node's PCIe fabric — ACS is the PCIe feature that isolates and redirects peer-to-peer traffic between devices, and a violation means some device attempted a peer-to-peer transfer that broke that isolation policy. This is the count of this specific error type accumulated during the most recently completed 1-day collection window for this compute node, which is what lets an admin tell whether the fault is a one-off blip or actively recurring at that timescale. For example, a jump from 0 to 2 in this 1-day window would point to something like e.g. a non-compliant mezzanine card attempting direct peer-to-peer DMA that the platform's ACS policy blocks and flags happening twice during that period specifically, rather than a single lingering old error.