well, obviously this is an airbus wing. so maybe it's an engineer's safety whatever.
BUT the B737NG with it's fancy swing-open overwing emergency exits has an emergency rope stored in the frame of the aft (if there are two) door/window frame. the book says:
"... they serve as a temporary steadying grip on the wings for the pax AFTER DITCHING..... ABP snaps hook in yellow painted fitting on the wing"
why? because it is assumed that after a ditching the trailing edge flaps are a mess and torn to sharp bits, so the pax go swimming via the leading edge.
and if this is an airbus-harness-thing, what if u have to work on the far end of the wing???? if u take a 10 meter rope u might as well fall of the side!