This is the per-MEP scoping of the CCM-transmitted counter, tracking exactly one MEP's heartbeat output rather than the chassis-wide or per-service totals seen elsewhere in this MIB. Because CCM transmission should be perfectly steady once a MEP is enabled, one frame per configured interval, no more and no less, this is the counter an admin checks first when suspecting a specific MEP has stopped sending heartbeats, since it isolates that one MEP's behavior from every other MEP sharing the same service or interface. A MEP configured for a 1-second CCM interval should show this counter increase by exactly 60 every minute; anything else means that individual MEP's transmit timer has drifted or stalled.