This is the second-stage CRC check performed after the HDLC CRC check, computed after decryption and payload decompression, so failures here are specifically attributed to 3xDES and payload compression problems. Because this is explicitly separated from the earlier HDLC-layer CRC check, a rising count here -- while the HDLC CRC counter stays low -- narrows the fault to the decryption/decompression stage rather than the raw satellite link, pointing an admin toward a possible encryption key mismatch or corrupted compression state rather than RF signal quality. If two ends of an encrypted link have their 3xDES keys fall out of sync after a configuration change, this counter would start climbing sharply even though the HDLC-layer CRC checks, and the RF signal itself, remain clean.