This read-write field is an action trigger an admin writes to manually control backup-trunk activation outside of automatic failure-triggered logic, with four distinct commands: initCmd and termCmd to immediately start or stop an operator-commanded backup, and initSched and termSched to start or stop a scheduled backup. An admin uses this for planned maintenance windows on the primary trunk, deliberately forcing traffic onto the backup path without waiting for lportTrkFailureThrsh to detect an actual failure. For example, writing initCmd(1) to lportTrkManualBu lets an admin proactively move traffic to the backup trunk before performing scheduled maintenance on the primary, then writing termCmd(2) afterward to restore normal operation.