Document ID: chunk:federal_register_of_legislation:F2023C00136:reg:113:p4
Version: federal_register_of_legislation:F2023C00136
Segment Type: reg
Provision Reference: reg 113 (pt 4/21)
Character Range: 25848–28706

clouds;
2.5.16. "Rear fog lamp" means the lamp used to make the vehicle more easily visible from the rear in dense fog;
2.5.17. "Daytime running lamp" means a lamp facing in a forward direction used to make the vehicle more easily visible when driving during daytime.
2.5.18. "Interdependent lamp system" means an assembly of two or three interdependent lamps providing the same function.
         2.5.18.1. "Interdependent lamp marked "Y"" means a device operating as part of an interdependent lamp system. Interdependent lamps operate together when activated, have separate apparent surfaces in the direction of the reference axis and separate lamp bodies, and may have separate light source(s).
2.5.19. "Lamps marked "D"" means independent lamps, approved as separate devices in such a way that they are allowed to be used either independently or in an assembly of two lamps to be considered as a "single lamp".
2.6. "Light-emitting surface" of a "lighting device", "light-signalling device" or a retro-reflector means all or part of the exterior surface of the transparent material as declared in the request for approval by the manufacturer of the device on the drawing, see Annex 3;
2.7.  "Illuminating surface" (see Annex 3);
2.7.1. "Illuminating surface of a lighting device" (paragraphs. 2.5.6., 2.5.7. and 2.5.15. above) means the orthogonal projection of the full aperture of the reflector, or in the case of headlamps with an ellipsoidal reflector of the "projection lens", on a transverse plane. If the lighting device has no reflector, the definition of paragraph 2.7.2. below shall be applied. If the light emitting surface of the lamp extends over part only of the full aperture of the reflector, then the projection of that part only is taken into account.
In the case of a passing-beam headlamp, the illuminating surface is limited by the apparent trace of the cut-off on to the lens. If the reflector and lens are adjustable relative to one another, the mean adjustment should be used;
In the case where any combination of a headlamp producing the principal passing-beam and additional lighting units or light sources designed to produce bend lighting are operated together, the individual illuminating surfaces, taken together, constitute the illuminating surface.
2.7.2. "Illuminating surface of a light-signalling device other than a retro-reflector" (paragraphs 2.5.8., 2.5.9., 2.5.11., 2.5.12., 2.5.14. and 2.5.16. above) means the orthogonal projection of the lamp in a plane perpendicular to its axis of reference and in contact with the exterior light-emitting surface of the lamp, this projection being bounded by the edges of screens situated in this plane, each allowing only 98 per cent of the total luminous intensity of the light to persist in the direction of the axis of reference. To determine the lower, upper and lateral