sdpBindControlWordBit specifies whether the use of the
'ControlWord' is preferred or not. The value of
sdpBindControlWordBit is exchanged with LDP peer during
pseudowire negotiation time. The default value is
determined by sdpBindVcType. sdpBindVcType of atmSdu and
frDlci must have default value of 'true'. Other values of
sdpBindVcType must have default value of 'false'.