Document ID: chunk:federal_register_of_legislation:F2007C00078:body:0:p9
Version: federal_register_of_legislation:F2007C00078
Segment Type: other
Provision Reference: 
Character Range: 25345–28117

means the orthogonal projection of the light-emitting surface on a plane perpendicular to the direction of observation;

2.8. "axis of reference" (or "reference axis") means the characteristic axis of the light signal determined by the manufacturer of the lamp for use as the direction reference (H = 0°, V = 0°) for angles of field for photometric measurements and for installing the lamp on the vehicle;

2.9. "centre of reference" means the intersection of the axis of reference with the light emitting surface; it is specified by the manufacturer of the lamp;

2.10 "angles of geometric visibility" means the angles which determine the minimum solid-angle zone in which the apparent surface of the lamp must be visible; this solid-angle zone is defined by the segments of the sphere of which the centre coincides with the centre of reference of the lamp and the equator is parallel to the ground; these segments are determined in relation to the axis of reference; the horizontal angles ß correspond to the longitude and the vertical angles a to the latitude. There must be no obstacle on the inside of the angles of geometric visibility to the propagation of light from any part of the apparent surface of the lamp. No account is taken of obstacles existing at the time of approval, where required, of the lamp;

2.11. "extreme outer edge", on either side of the vehicle means the plane parallel to the median longitudinal plane of the vehicle and touching the lateral extremity of the vehicle, disregarding the projection or projections;

2.11.1. of rear-view mirrors;

2.11.2. of direction indicator lamps;

2.12. "over-all width" means the distance between the two vertical planes defined in paragraph 2.11. above;

2.13.  "a single lamp" means any assembly of two or more lamps, whether identical or not, having the same function and emitting light of the same colour, which is constituted by devices whose lamps have illuminating surfaces which, on the same transverse plane, occupy not less than 60% of the area of the smallest rectangle circumscribing the said illuminating surfaces, provided that such assembly is approved as a single lamp where approval is required. This definition does not apply to driving lamp, the passing lamp or the front fog lamp;

2.14. "distance between two lamps which face in the same direction", the distance between the orthogonal projections in a plane perpendicular to the axes of reference of the outline of the two illuminating surfaces as defined according to the case mentioned in paragraph 2.6.;

2.15. "'operating' tell-tale" means a tell-tale showing that a device has been switched on and is operating correctly;

2.16. "'circuit-closed' tell-tale" means a tell-tale showing that a device has been switched on, but not