This read-write INTEGER object identifies a PVC as primary or secondary within a protection group, where the primary must be added before the secondary and deleted only after it, and where the primary becomes active while the secondary becomes standby once the group is set up; this distinction is only meaningful when the PVC is protected. Getting the add/delete order wrong for primary versus secondary would violate the required sequencing for setting up or tearing down a protection group. An engineer building a redundant PVC pair would always configure and add the primary PVC before adding the secondary, and reverse that order when removing them.