Right this mite be the the way it came around in the early days offshore the Scaffold firms were Mills and Sgb they did not hire out any of there fittings and up till about 15 + years Sgb only stared to sell its Band in plate if you worked with Sgb every Transome on any job had to be fitted with band in plate singles were only for toe boards, same With Mills every set of standard with Mills 90s and hooks for intermediates and hooks for toes boards so then came Aberdeen Scaffold in the 1980s they only started out with Doubles and singles so they would put in under each nod point suplementary transome so this got the slang name aberdeen tranny to this day ???????