This is a bitmask, one bit per physical CPU core (core0 through at least core15 per the truncated syntax), where a set bit means that specific core's utilization has crossed the module's configured high-utilization threshold, as the description states. Because the mask flags individual cores rather than reporting a module-wide average, it lets an admin distinguish a single hot core - often a sign of a process pinned to one core via interrupt or CPU affinity - from genuine module-wide CPU exhaustion that would set most or all of the bits at once. A returned mask with only the core3 bit set (0x08) while cores 0, 1, and 2 stay clear would point at a single runaway process bound to core 3 rather than a general overload.