Waahhh.... damn observant of you Chinozie. I remember it is an alignment hole for the headlights. What i don't know is if that it is used only for manufacturing or for on car headlight adjustments.
Also for 1 piece headlight with integrated bulb (very old cars only, like mine) the marking hole is non existent. Meaning the lights are aligned at factory.
The horizontal or vertical stripes are to refract a little light so the beams are not direct in 1 lighting zone. Newer lights uses the rear multi-reflectors to refract light with clear front screen. The older lights uses the lense to refract light with clear flat surfaced reflector. Look at the SEG/LE light againsts the Myvi one.
Does that help?