This read-write value sets or reports the VCI (Virtual Channel Identifier) value used in the ATM cell header for this leaf's connection, the other half of the VPI/VCI pair alongside cktLeafAtmVPI. Together these two values fully specify the ATM virtual circuit identity on the physical link for this leaf, and being read-write allows explicit provisioning to match a specific value required by connected equipment. An engineer provisioning a leaf toward a CPE that expects VCI 35 on VPI 0 (a common default UNI signaling channel convention) would set cktLeafAtmVCI to 35 to match that expectation.