Tariff
A tariff is called an optimal tariff if it's set to maximize the welfare of the country imposing the tariff. It is a tariff derived by the intersection between the "trade indifference curve" of that country and the offer curve of another country. In this case, the welfare of the other country grows worse simultaneously, thus the policy is a kind of "beggar thy neighbor policy". If the offer curve of the other country is a line through the origin point, the original country is in the "condition of a small country", so any tariff worsens the welfare of the original country.
Schedules of concessions
Schedules of concessions are documents in which the specific commitments are listed. World Trade Organization (WTO) negotiations produce general rules that apply to all members, and specific commitments made by individual member governments. For trade in goods in general, these consist of maximum tariff levels. For agriculture they also include tariff quotas, limits on export subsidies, and some kinds of domestic support. The goods schedules are annexed to the General Agreement on Tariffs and Trade (GATT) and are “bound” (GATT Article II).