In medieval Europe, a riverside town where
merchants had to offer their wares for sale
before proceeding to their destination, a
practice that constituted a form of toll;
such towns were particularly common on the
Rhine. In English usage, it referred to a
town appointed as the exclusive market for a
particular commodity, especially wool. The
wool staple was established by the English
crown in Calais 1353. This form of monopoly
trading was abandoned 1617.