This read-only Unsigned64 records the lowest per-interval delta of internal MAC receive errors observed across all collected sampling intervals recorded in this one archived historical sample of an interface's error-statistics -- effectively the quietest interval seen so far. For a healthy link this minimum should sit at zero, so admins use it as a sanity check that the interface has at least some clean intervals rather than a constant, low-level error rate, since a rising count here implicates the local silicon on this specific adapter or IOM port rather than the cable, which is exactly why UCS breaks this counter out separately from the wire-level ones. A minimum value that's stuck above zero on this port -- meaning not even one polling interval came back completely clean -- indicates a persistent, not intermittent, problem.