Explanation:

Aggregate measurement of support (AMS) is the indicator on which the domestic support discipline  for the Uruguay Round Agreement on Agriculture is based. It is determined by calculating a market price support estimate for each commodity receiving such support, plus non-exempt direct payments or any other subsidy not exempted from reduction commitments, less specific agricultural levies or fees paid by producers. The main conceptual consideration is that there are basically two categories of domestic support — support with no, or minimal, distortive effect on trade on the one hand (often referred to as “Green Box” measures) and trade- distorting support on the other hand (often referred to as “Amber Box” measures). For example, government provided agricultural research or training is considered to be of the former type, while government buying-in at a guaranteed price (“market price support”) falls into the latter category. Under the Agreement on Agriculture, all domestic support in favour of agricultural producers is subject to rules. In addition, the aggregate monetary value of Amber Box measures is, with certain exceptions, subject to reduction commitments as specified in the schedule of each WTO Member providing such support.