" but got stuck when he pointed out the yellow painted eyelets on the upper wing."
For the A320, these are anchor points for a rope stowed in the narrow doored over head stowage, around the o/wing area, have noticed that the ropes are not on all operaters aircraft.
I'll follow up later.
And yes the B737 Classic has the rope in the top corner of the cut out for the O/wing hatch.