Military Abbreviations on Australian War Records Explained

You've downloaded your ancestor's service record from the National Archives. You've opened it. And now you're staring at a page of handwritten abbreviations that look like someone's cat walked across a telegraph machine. TOS. SOS. M/I. B103. GSW. HMAT. AWL. FP1.

Military service records weren't written for families. They were administrative documents created by clerks to track personnel movements, and those clerks used abbreviations for everything because they were writing the same entries hundreds of times a day. The result is a document that's dense, cryptic, and incredibly frustrating for anyone who isn't already fluent in early 20th-century military shorthand.

This guide decodes the most common abbreviations you'll find on Australian WWI and WWII service records. It's organised by category so you can find what you're looking for quickly. Bookmark it - you'll be back.

Movements and postings

These are the abbreviations you'll see most often on the service and casualty form (Form B103). They track where a person went and when.

Casualties and medical

Hospitals and medical facilities

Ranks

Units and formations

Discipline and administration

Ships and transport

Honours and awards

Common location abbreviations

Beyond the abbreviations

This list covers the most common abbreviations, but it's just the starting point. A service record isn't only abbreviations - it's handwriting, dates, unit codes, and administrative notations that require historical context to interpret properly. Knowing that TOS means "Taken On Strength" doesn't tell you what the 2/14th Battalion was doing on that date, where they were stationed, or what your ancestor would have experienced.

Decode My Digger goes beyond the abbreviations. It takes every line of a service record and maps it against the historical record: the unit war diaries, the campaign histories, the embarkation rolls. The result isn't just a translation - it's a contextualised narrative that connects abbreviations to real events.

For further reference, the NAA's official abbreviations list and the AWM Glossary are also valuable resources.

Frequently asked questions

What does TOS mean on an Australian war record?

TOS stands for "Taken On Strength". It means the person was formally added to a unit's roll. When you see "TOS 2/14 Bn", it means they were posted to the 2nd/14th Battalion. It's one of the most common entries on the service and casualty form.

What does SOS mean on an Australian service record?

SOS stands for "Struck Off Strength" - the opposite of TOS. It means the person was formally removed from a unit's roll. This could be because they transferred, were hospitalised, went on leave, were discharged, or were killed. It doesn't necessarily mean they left the army.

What does M/I mean on a war record?

M/I stands for "Marched In" - the person physically arrived at a unit or location. M/O means "Marched Out" - they departed. These terms date from when soldiers literally marched between locations. On a service record, M/I is often used interchangeably with TOS.

What does RTA mean on an Australian military record?

RTA stands for "Returned to Australia". It means the person completed their overseas service and came home. You'll commonly see it on WWI nominal rolls alongside KIA (Killed in Action), DOW (Died of Wounds), and DOD (Died of Disease).

What does AWL mean on a service record?

AWL stands for "Absent Without Leave". The person failed to report back to their unit on time. It's a disciplinary offence and is usually followed by a punishment notation such as FP (Field Punishment), CB (Confined to Barracks), or forfeiture of pay.

What does HMAT mean?

HMAT stands for "His Majesty's Australian Transport" - an Australian troopship. If you see "EMB HMAT Themistocles" on a record, it means the person boarded the troopship Themistocles to go overseas.