| Asian Technology Conference in Mathematics | Academic & Science |
| Association of Town Centre Management | Business |
| Art Theory Criticism and Management | Business |
| Aeronautical Time Cycle Management | Business |
| Association of Town Center Management | Business |
| Active Treatment Crisis Management | Business |
| Association of Town and City Management | Business |
| Adventure Travel Conference and Mart | Community |
| Association of Technical Collaborative Media | Community |
| Antarctic Treaty Consultative Meeting | General |
| Antarctic Treaty Consultative | General |
| Airborne Toxic Control Measures | General |
| Airborne Toxic Control Measure | General |
| Automatic Tube Current Modulation | General |
| Antarctic Treaty Consultative Meetings | General |
| Aspera Transfer Cluster Manager | General |
| Air Toxics Control Measure | General |
| ARBURG Turnkey Control Module | General |
| Asymmetrical Triangular Current Mode | General |
| Architectural Technology and Construction Management | General |
| Adaptive Track Control Model | General |
| Automatic Temperature Control Module | General |
| Automatic Transmission Control Module | General |
| All Terrain Control Module | General |
| Automobile et Touring Club de Montreal | General |
| Automobile and Touring Club of Mozambique | General |
| Advanced Training for Counseling Ministry | Governmental |
| Akademie für Traditionelle Chinesische Medizin | International |
| Association of Traditional Chinese Medicine | Medical |
| Advanced Techniques in cosmeceuticals Medications | Medical |
