This is not to say that, in unionized situations, the pay of machinists is immediately reduced to operator levels the moment numerical control is introduced. In some exceptional instances, where very few numerically controlled machine tools have been brought into a shop, the union has been able successfully to insist that the entire job, including programming and coding, be handled by the machinist. In many other cases, the pay scale of the machinist has been maintained or even increased by the union after the introduction of numerical control, even though he has become no more than an operator. But such pay maintenance is bound to have a temporary character, and is really an agreement, whether formal or not, to “red circle” these jobs, as this is known in negotiating language; that is, to safeguard the pay of the incumbents. Management is thus sometimes forced to be content to wait until the historical process of devaluation of the worker’s skill takes effect over the long run, and the relative pay scale falls to its expected level, since the only alternative to such patience is, in many cases, a bitter battle with the union.