| A/B | Able Seaman |
| A/V | Absent Voter Electoral Records Aug & Oct 1918 |
| AA | Anti-Aircraft |
| AA & QMG | Assistant Adjutant and Quartermaster General |
| AASC | Anti-Aircraft Searchlight Company |
| AASS | Anti-Aircraft Searchlight Section |
| AB | Army Book |
| ABPO | Advanced Base Post Office |
| ACC | Army Cyclist Corps |
| ACG | Assistant Chaplain General |
| ACI | Army Council Instruction |
| AD | (or Art. Dpt) Artillery Depot |
| ADAPS | Assistant Director Army Postal Services |
| ADC | Aide de Camp |
| ADGT | Assistant Director-General of Transportation |
| ADL | Assistant Director of Labour |
| ADLR | Assistant Director of Light Railways |
| ADMS | Assistant Director Medical Services |
| ADOS | Assistant Director Ordnance Services |
| ADRT | Assistant Director Railway Traffic |
| ADS | Advanced Dressing Station |
| ADTN | Assistant Director Transportation |
| ADVS | Assistant Director Veterinary Services |
| AEC | (or A. Emp. Coy) Area Employment Company |
| AF | Army Form |