This read-only counter reports the number of Coding Violations recorded on the interface during one completed 15-minute (or daily) performance-monitoring interval, as identified by the row's PM type, direction, and interval-number index. An admin trends this across the stored intervals to spot line-coding errors creeping up on a transponder or optical port before they escalate into service-affecting faults. A jump from near-zero CVs to several thousand in one interval on a given port flags a signal-quality problem worth investigating with a physical-layer test.