((a)) ** Cost-of-living increase and additional compensation** Under regulations which shall be prescribed by or under authority of the President, each teacher (other than a teacher employed in a substitute capacity) shall be entitled, in addition to basic compensation, to—
((1)) cost-of-living allowances equal to those authorized by , and
((2)) additional compensation equal to that authorized under .
((b)) ** Post differential** The cost-of-living allowances and additional compensation provided under subsection (a) of this section for any teacher shall be based on the teaching position in which he rendered services on a school-year basis, except that, if such teacher is employed in another position during any recess period between two school years, such allowances and compensation for such recess period shall be based on the position in which he is employed during such recess period.