Requirements for Authorisation D Issue Date March 2019 85 ii) additional equipment fitted in the standing area must comply with the +mm level requirement b) rails certified as level to within +/- mm and parallel to the standing area. The rails must be straight and the headlamp tester must not have significant rock or twist at any point along the rails. The certificate fora' and 'b' above must show height measurement from a level plane at all intersecting points on a 300 mm (max) square grid covering the standing area and at points mm (max) apart on the rails. It must be signed by a competent person, such as a surveyor, manufacturer’s representative or agent and include date, status, address of firm and VTS address. A copy must be provided to DVSA for the garage file c) mm clearance behind the headlamp aim tester optical head. Floor mounted equipment must not be installed in this area d) the standing area must be durably and clearly marked with a datum line (or lines) at the headlamp tester manufactures operational tolerance limits for positioning the vehicle headlamp in relation to the headlamp tester. 3.3 Headlamp aim equipment operating instructions must be available.