As prescribed in 231.100-70, use the following clause:
Supplemental Cost Principles (DEC 1991)
When the allowability of costs under this contract is determined in accordance with part 31 of the Federal Acquisition Regulation (FAR), allowability shall also be determined in accordance with part 231 of the Defense FAR Supplement, in effect on the date of this contract.
(End of clause)
48 C.F.R. §§252.231-7000