Strikes and lock-outs are illegal if begun or continued contrary to the Code or a prohibition order. Strikes and lock-outs are illegal if commenced or declared in contravention of the Code or continued contrary to an order under section 42(7). Where a strike or lock-out began before filing or reference to a Tribunal and was not unlawful at commencement nor prohibited under section 42(7), its continuance is not deemed illegal. A lock-out in consequence of an illegal strike, or a strike in consequence of an illegal lock-out, is not deemed illegal.