When the importation of a commodity is limited to a definite quantity, the trade control means used is known as

The trade control means used when the importation of a commodity is limited to a definite quantity is called "quotas." This means that the government or regulatory body imposes a restriction on the amount of a particular product that can be imported into a country during a specified period. Quotas are used to regulate the flow of goods into a country's market and can be applied to both exports and imports. They are typically used when a government wants to protect domestic industries from foreign competition, or when it wants to limit the impact of a particular product on the environment or public health. For example, a country might impose a quota on the amount of foreign steel that can be imported, in order to protect its own steel industry from foreign competition. Or, a country might limit the amount of certain chemicals or food products that can be imported, in order to protect public health or the environment. Overall, quotas are a way for governments to manage trade flows in a controlled manner, while also protecting domestic industries and public interests.