This identifies which specific ATM threshold-crossing alert, ingress uncorrectable HEC error, egress CBR/ABR/VBR1/VBR2 buffer overflow, ingress framer FIFO overflow, or egress lookup failure, was most recently declared on this port. Rather than polling every individual TCA threshold object described above, this single field on this specific port tells you at a glance which particular condition just fired, cutting straight to the relevant counter and threshold pair for further diagnosis. A value of egressVBR2BufferOverflowC here means this port's most recent ATM TCA was specifically a VBR2 egress buffer overflow, directing attention to pportATMTcaEBufOverflowVBR2Thresh and its related counter rather than any of the other traffic classes.