Quotas and Quota System

Absolute quotas permit a limited number of units of specified merchandise
to be entered or withdrawn for consumption during specified periods.
Tariff-rate quotas permit a specified quantity of merchandise
to be entered or withdrawn at a reduced rate during a specified period.
Quotas are established by Presidential Proclamations, Executive Orders, or
other legislation.

The Quota System, a part of Customs' Automated Commercial System, controls
quota levels (quantities authorized) and quantities entered against those
levels. Visas control exports from the country of origin. Visa
authorizations are received from other countries and quantities entered
against those visas are transmitted back to them. Control of visas and
quotas simplify reconciliation of other countries' exports and U.S.
imports.