This string names the previous stage or state the finite-state-machine for this internal backplane link was in before its current one. It matters on the internal Ethernet link that carries a blade's traffic from the chassis I/O Module up to a Fabric Interconnect over the backplane because knowing the prior stage helps an admin tell whether the FSM is progressing normally toward completion or has looped back after a failure. An fsmPrev value indicating a retry stage on this backplane link suggests the workflow already failed once and is attempting the step again, which is worth flagging if it keeps recurring.