I think he means color codes. I saw same way of engineering at color coding power connections for submersible Grundfos pumps, leading to same (albeit less deadly) results.
Back to Tu-154, if I recall correctly, it's power wiring of damping motors and they must work in antiphase to input signals, so they used cheap solution. IIRC there was a Tupolev's bulletin to remark them after this "dance".