((a)) ** .—** Except as provided in this section, sections 627 through 632 of this title shall apply to promotions of officers in competitive categories of officers designated for purposes of this subchapter.

((b)) ** .—** The reference in to an officer above the promotion zone shall not apply in the promotion of officers described in subsection (a).

((c)) ** .—** The reference in to a person above the promotion zone shall not apply in the promotion of officers described in subsection (a).

((d)) ** .—** In the administration of this subchapter pursuant to subsection (a)—

((1)) an officer described in subsection (a) shall not be deemed to have failed twice of selection for promotion for purposes of until the officer has failed selection of promotion to the next higher grade the maximum number of times specified for opportunities for promotion to such grade within the competitive category concerned pursuant to ; and

((2)) any reference in section 631(a) or 632(a) of this title to an officer who has failed of selection for promotion to the next higher grade for the second time shall be deemed to refer instead to an officer described in subsection (a) who has failed of selection for promotion to the next higher grade for the maximum number of times specified for opportunities for promotion to such grade within the competitive category concerned pursuant to such section 649d.