If an applicant performs the skills test in a vehicle equipped with air over hydraulic brakes, the State must indicate on the CDL, if issued, that the person is restricted from operating a CMV equipped with any braking system operating fully on the air brake principle. For the purposes of the skills test and the restriction, air over hydraulic brakes includes any braking system operating partially on the air brake and partially on the hydraulic brake principle. (Even if it is air over hydraulic, you are still required to take the air brake written test.)