This is a 64-bit high-capacity counter tracking transmitted VSL packets with checksum errors, avoiding 32-bit wraparound on a busy link. An admin cares because it provides a wraparound-safe way to trend physical-layer corruption on a high-throughput VSL over long polling intervals. For example, an admin trending checksum error rates over a week-long baseline would rely on this counter rather than the smaller 32-bit counter to avoid a misleading rollover.