- vision for objects that a 20 feet or more from the viewer
- Observation: all-round observation; proper use of mirrors; far, middle, near distance vision;
- a is the distance in millimetres between the component obstructing vision and the reference point measured along the visual radius joining the reference point, the centre of the component and the perimeter of the semi-circle of vision; and
- for binocular vision with an inter-ocular distance of 65 mm, the masking effect expressed in mm is given by the formula:
- For the purpose of determining the masking effects in the sector of vision, the masking effects due to the frame of the windscreen and to any other obstacle may, in accordance with the provisions of point 188.8.131.52, be considered as a single effect, provided that the distance between the outermost points of this masking effect does not exceed 700 mm.