| UGA | Unitary Group Approach |
| GUGA | Graphical Unitary Group Approach |
| IBA | Independent Broadcasting Authority |
| ISA | International Search Authority |
| KTA | Korean Telecommunication Authority |
| cea | County Education Authority |
| CAA | Civil Aviation Authority [U.K.] London, http://www.caa.co.uk |
| CA | Certification Authority [engl.] Berechtigte Stelle zur Bestätigung digitaler Schlüssel |
| LSA | Local Security Authority |
| MTA | Metropolitan Transportation Authority |
| NAPTR | Naming Authority Pointer |
| SAS | Signature Authority System |
| AHJ | Authority Having Jurisdiction [engl.] Kommunale Inspektoren |
| SOA | Start Of [zone of] Authority [DNS] |
| TVA | Tennessee Valley Authority |
| LEAF | Linking and Exploring Authority Files |
| IANA | Internet Assigned Numbers Authority |
| HEA | Health/Higher Education Authority |
| A.D.E. | Atomic Energy Authority [engl.] Britische Atombehörde |
| AAIC | Accounting Authority Identification Code Abrechnungskennung bei Gesprächsanmeldung über eine Küstenfunkstelle |
| AATA | Ann Arbor Transportation Authority [engl.] Ann Arbor, [MI], http://www.theride.org |
| AFI | Authority and Format Identifier [engl.] Teil der IDP im ATM-Standard |
| ARL | Authority Revocation List [engl.] |
| ASA | Advertising Standard Authority [engl.] Britische Behörde zur Überwachung der Werbung |
| AUC | Authentication/Authority Centre [engl.] |
| BAA | British Airport Authority [engl.] Britischer Flughafenverband |
| BTA | British Tourist Authority [engl.] |
| FAID | Flash Authority Identification Data |
| FLRA | Federal Labor Relations Authority |
| FPHA | Federal Public Housing Authority |
| PCA | Policy Certification Authority [im Deutschen Forschungsnetz] Hamburg, http://www.dfn-pca.de |
| UKAEA | United Kingdom Atomic Energy Authority Culham, http://www.ukaea.org.uk |