ferences based upon such matters as the unit within which seniority is to be computed, the privileges to which it shall relate, the nature of the work, the time at which it is done, the fitness, ability or age of the employees, their family responsibilities, injuries received in course of service, and time or labor devoted to related public service, whether civil or military, voluntary or involuntary. See, e. g., Hartley v. Brotherhood of Clerks, 283 Mich. 201, 277 N. W. 885; and see also, Williamson & Harris, Trends in Collective Bargaining (1945), 100-103.
The National Labor Relations Act, as amended, gives a bargaining representative not only wide responsibility but authority to meet that responsibility. We have held that a collective-bargaining representative is within its authority when, in the general interest of those it represents, it agrees to allow union chairmen certain advantages in the retention of their employment, even to the prejudice of veterans otherwise entitled to greater seniority. Aeronautical Lodge v. Campbell, supra, at 526-529.
The public policy and fairness inherent in crediting employees with time spent in military service in time of war or national emergency is so clear that Congress, in the Selective Training and Service Act of 1940, required some credit to be given for it in computing seniority both in governmental and in private employment. See note 5, supra. Congress there prescribed that employees who left their private civilian employment to enter military service should receive seniority credit for such military service, provided their prior civilian employment, however brief, was bona fide and not on a temporary basis. There is little that justifies giving such a substantial benefit to a veteran with brief prior civilian employment that does not equally justify giving it to a veteran who was inducted into military service before having a chance to enter any civilian employment, or to a veteran who never worked