Requirements for Authorisation D Issue Date March 2019 60 b) rails certified as being flat and level to within mm and parallel to the forward edge of the standing area. The rails must be straight and the headlamp tester must not have excessive rock The certificate fora and b above must show height measurements from a level plane at all intersecting points on a mm (max) square grid covering the standing area and at points mm apart on the rails, which must be within the limits stated. It must be signed by a competent person i.e. 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 placing on the garage file c) equipment positioned to take account of the vertical and horizontal location of headlamps tested, the standing area and datum lines) d) clearance at the rear of the tester optical head to beat least mm e) 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. A centre line on the standing area at right angles to the datum line is required. 3.3 Headlamp aim equipment operating instructions must be available. 3.4 Suitable arrangements for checking the alignment of the equipment with the standing area must be in place. These may consists of evidence provided by a competent outside agency or by the VTS using the manufacturer's acceptable equipment. Provision must be made for checks to be carried out at no more than 6 monthly intervals and for records to be kept. It is acceptable if an alignment check is within the 6th calendar month in which the alignment was last checked.