‘Illuminating surface of a light-signalling device other than a retro-reflector’ (paragraphs 2.7.11. to 2.7.15., 2.7.18., 2.7.20. and 2.7.22. to 2.7.25) 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.
valgussignaalseadme, välja arvatud helkurid, valgusava (punktid 2.7.11–2.7.15, 2.7.18, 2.7.20 ja 2.7.22–2.7.25) — laterna ortogonaalprojektsioon pinnal, mis asetseb risti laterna nullteljega ning on kokkupuutes laterna välise valgust kiirgava pinnaga ning mis piirneb kõnealusel tasandil paiknevate ekraanide servadega, millest igaüks laseb läbi ainult 98 % kogu valgustugevusest nulltelje suunas.