The International Air Transport Association (IATA) developed and maintains 2-digit and 3-digit codes for air carriers. The U.S. Census Bureau created a 4-digit air carrier code. Automated Export System (AES) and Automated Broker Interface (ABI) participants must report either the 2-digit IATA or the 3-digit IATA code. The AES and ABI systems will not accept the Census Bureau's codes. See a list of air carrier codes.