Then there are a variety of concessions, exemptions, and surcharges.

Quality used to be included in the price of a ticket now, with surcharges for seat selection, meals, and the like, customers are charged for it separately.

Some are directly trade related (e.g. import quotas, import surcharges, anti dumping measures), others have a link to trade in as far as their implementation is monitored at the border (e.g. labelling, packaging, sanitary standards), while a third group arises from general public policy (e.g. government procurement, investment restrictions, extent of intellectual property right protection).