(2) Except as authorized by subchapter I of chapter
35 of title
5, changes in the salary class of a member of the Senior Foreign Service or a member of the Service assigned to a salary class in the Foreign Service Schedule shall be made only in accordance with subchapter VI of this chapter. The Secretary shall prescribe regulations (which shall be consistent with the relevant provisions of subchapter VI of chapter
53 of title
5 and with the regulations prescribed to carry out such provisions) providing for retention of pay by members of the Service in cases in which reduction-in-force procedures are applied.