If the maintenance protocol is used for VC establishment, this parameter indicates the received status of control word usage, with notYetKnown used while the maintenance protocol has not yet received the indication from the remote node. This tells the admin whether the far end has actually confirmed it will send packets with or without the control word header, and seeing this stuck at notYetKnown well after the pseudowire should have completed signaling is itself a diagnostic clue that the signaling exchange with the remote PE has not fully completed. For example, a pseudowire reporting withControlWord(2) here confirms the remote PE will indeed prepend the control word to every packet it sends, which the local PE's own decapsulation logic must be configured to expect and correctly strip.