Exactly as described, this counts received packets shorter than 64 octets that also carried a bad FCS or a non-integral-octet alignment error -- true corrupted fragments, not just undersized-but-valid frames. Because this combines both the undersize condition and a checksum or alignment failure, a rising count here, as opposed to the undersize-only counter, points specifically toward physical-layer corruption -- bad cabling, a failing SFP, or a duplex mismatch -- rather than a benign test-configuration artifact. For example, fragment counts rising in lockstep with degrading throughput results on an otherwise correctly-configured test would be the classic signature of a marginal fiber connector needing to be reseated or cleaned.