For the purposes of sub-headings 5209 42 and 5211 42, the expression “denim” means fabricss of yarns of different colours, of 3 – thread or 4 – thread twill, including broken twill warp faced, the warp yarns of which are of one and the same colour and the weft yarns of which are unbleached, bleached, dyed, grey or coloured a lighter shade of the colour of the warp yarns.