(2) For the purposes of paragraph (iv) of subdivision (1), the Board, with the cooperation of employers and employees, shall secure the establishment of standards determining the physical and mental conditions which permanently disqualify employees for work in the several occupations in the railroad industry, and the Board, employers, and employees shall cooperate in the promotion of the greatest practicable degree of uniformity in the standards applied by the several employers. An individual’s condition shall be deemed to be disabling for work in his regular occupation if he will have been disqualified by his employer for service in his regular occupation in accordance with the applicable standards so established; if the employee will not have been so disqualified by his employer, the Board shall determine whether his condition is disabling for work in his regular occupation in accordance with the standards generally established; and, if the employee’s regular occupation is not one with respect to which standards will have been established, the standards relating to a reasonably comparable occupation shall be used. If there is no such comparable occupation, the Board shall determine whether the employee’s condition is disabling for work in his regular occupation by determining whether under the practices generally prevailing in industries in which such occupation exists such condition is a permanent disqualification for work in such occupation. For purposes of this subdivision and paragraph (iv) of subdivision (1), an employee’s “regular occupation” shall be deemed to be the occupation in which he will have been engaged in more calendar months than the calendar months in which he will have been engaged in any other occupation during the last preceding five calendar years, whether or not consecutive, in each of which years he will have earned wages or salary, except that, if an employee establishes that during the last fifteen consecutive calendar years he will have been engaged in another occupation in one-half or more of all the months in which he will have earned wages or salary, he may claim such other occupation as his regular occupation.
45 USC § 231a(a)(2)
None identified, default scope is assumed to be the parent (subchapter IV) of this section.