What are working / functional buttons?
This refers to the buttons on the sleeves of a jacket constructed so that the sleeve buttons & cuffs open. Functional buttonholes on a sleeve are considered the mark of a finely tailored custom garment. Trivia: Functional buttonholes were 1st introduced by the medical profession during the Crimean War & were known as surgeon cuffs. The cuffs & sleeves of a suit coat were folded up to prevent the suit coats of the surgeons from getting ruined by surgeries performed on the battlefield.