| AFA | Army Field Artillery; Australian Field Artillery |
| AG | Adjutant General |
| AGS | Army Gymnastic Staff |
| AIF | Australian Imperial Force |
| AIS | Assistant Inspector of Searchlights |
| AMFO | Assistant Military Forwarding Officer |
| AMLO | Assistant Military Landing Officer |
| AMO | Administrative Medical Officer |
| AMS | Assistant Military Secretary |
| ANZAC | Australian and New Zealand Army Corps |
| AO | Army Order |
| AOC | Army Ordnance Corps |
| AOD | Army Ordnance Department |
| AP | Armour Piercing (ammunition) |
| APC | Army Pay Corps and Assistant Principal Chaplain |
| APM | Assistant Provost Marshal |
| APO | Army Post Office |
| AQMG | Assistant Quartermaster-General |
| ARD | Alberta Reinforcement Depot |
| ARMW | Army Reserve Munition Worker |
| ARP | Ammunition Refilling Point |
| ARS | Advanced Regulating Station |
| ASC | Army Service Corps |
| ASD | Army Schools Department |
| ASO | Area Searchlight Officer |