Section 84. To each officer and enlisted person of the armed forces of the commonwealth required and authorized to travel under any section of this chapter, there shall be allowed and paid from funds appropriated therefor and under such regulations as the adjutant general may prescribe, the following:—

(1) For travel by privately owned motor vehicle, the current mileage rate authorized by law and any regulations pursuant thereto.

(2) For travel by rail or commercial airline, actual transportation expense.