Again, the case for the limitation or variation is apt to be the stronger, when the difference in advantage is between concentrated but widely separated areas, such as might exist between two ports, for example, than when the differences are between different units in the same industrial area or field. For in the second case, the possibility of causing lasting unemployment would be less. The distinction, however, is entirely one of degree. Whatever limitations or variations are admitted should not be settled arbitrarily; they should correspond to the facts which make them advisable. The union attitude in respect to the extension of wage standardization is sometimes as cautious as that of the employers. That is because those workers employed at the points which are supposed to possess the smaller advantages, natural or acquired, are not likely to support an unmodified application of the principle of standardization, unless they believe the consequent industrial changes will be beneficial, or at least not harmful, to themselves. The advice, if not the concurrence, of all interested parties is of the greatest value in arriving at a satisfactory determination. A good example of such an arrangement is to be found in the agricultural living wage legislation in Great Britain. It is provided therein that "When a district committee has been established for any area, it shall be the duty of the Committee to recommend to the Agricultural Wages Board, minimum rates of wages fixed under this act, and no variation or cancellation of such a rate shall have effect within that area unless ... recommended by the district wages committee."[88] 3.--Another possible ground for limitation or variation of the principle of standardization is set forth often in the contention that the character of the work performed by any large group of wage earners is not the same throughout the field of its employment. Such, for example, was the argument of the directors of the American railways, as summarized by Mr. Stockett: "... The railways oppose district standardization on the ground that rates cannot be disassociated from conditions and since conditions vary widely on different roads in such extensive territories as the railway districts they maintain that rates cannot be made uniformly applicable on all the roads. The amount of compensation, the roads hold, is governed by the labor performed, the skill and efficiency required, the responsibility and hazard involved, the discipline necessary, the rapidity of promotion, and the cost of living."[89]