You will be reimbursed on a mileage basis, plus per diem, not to exceed the total constructive cost of the authorized method of common carrier transportation plus per diem. Your agency must determine the constructive cost of transportation and per diem by common carrier under the rules in § 301-10.310.
Code of Federal Regulations
[FTR Amdt. 70, 63 FR 15955, Apr. 1, 1998, as amended by FTR Amdt. 2010-07, 75 FR 72967, Nov. 29, 2010]