Service personnel military files from the First World War contain many abbreviations and terms, the most common of which are explained here.
| Abbreviation | Term | Meaning |
| Acting or a/ | Acting Rank | higher rank held on a temporary basis - also known as a brevet rank for officers |
| Adj | Adjutant | administrative assistant to a commanding officer (below divisional level) |
| adm | admitted | soldiers entering hospital for medical treatment |
| ARD | Alberta Regimental Depot | facility in England used to assemble men and to store and administer equipment and materials |
| att’d | attached | to be made part of a specific unit on a temporary basis |
| auth | authorized, authority | designation of the individual or organization permitting the action noted |
| AWL or AWOL | absent without leave | away from a unit without permission; an offence under military law |
| Batt’n or Bn | Battalion | unit of approximately 1,000 men commanded by a lieutenant-colonel |
| BCRD | British Columbia Regimental Depot | facility in England used to assemble men and to store and administer equipment and materials |
| BEF | British Expeditionary Force | army of more than 3,000,000 men established by the Government of Britain for service overseas |
| Bde | Brigade | unit of approximately 4,000 men commanded by a brigadier-general |
| Bramshott | Bramshott | location of a Canadian military training base in Hampshire, England |
| Bty | Battery | artillery unit commanded by a major and composed of four or six guns or mortars |
| Boulogne | Boulogne | location of Canadian General Hospital (number three) in France |
| CADC | Canadian Army Dental Corps | corps of military dentists and other personnel providing dental services to soldiers |
| CAMC | Canadian Army Medical Corps | corps of military doctors, nursing sisters and other personnel providing medical treatment to soldiers |
| Canterbury | Canterbury | location of Canadian Military Hospital (number two) in Kent, England |
| CASC | Canadian Army Service Corps | branch of the military responsible for supplying troops in the field |
| Cav | Cavalry | soldiers who fought on horseback |
| CBD | Canadian Base Details | small units charged with maintaining and improving camp areas |
| CCAC | Canadian Casualty Assembly Centre | centre where wounded were assessed for either further treatment or return to duty |
| CCCC | Canadian Corps Composite Company | unit of men unfit for active duty at the front and attached to Corps Headquarters for employment |
| CCD | Canadian Convalescent Depot | facility where soldiers could recover from wounds and rebuild their strength |
| CCRC | Canadian Corps Reinforcement Centre | centre in France where troops were held before being sent to reinforce existing units |
| CCS | Casualty Clearing Station | first medical unit (after the Aid Post) for wounded soldiers evacuated from the front lines |
| CDD | Canadian Discharge Depot | centre in Canada where soldiers returning from war were released from service |
| CDAC | Canadian Divisional Ammunition Depot | railhead where divisional ammunition was stored before being shipped to the front |
| CE | Canadian Engineers | corps of men who built bridges, railway depots, camps, bases and other military installations |
| CEF | Canadian Expeditionary Force | force of more than 600,000 men established by the Government of Canada for service overseas |
| CERD | Canadian Engineer Reinforcement Depot | centre from which reinforcements were allocated to existing engineering units |
| CFA | Canadian Field Ambulance | unit responsible for evacuating the wounded from the front lines to medical centres |
| CFA | Canadian Field Artillery | organization responsible for using medium-calibre guns in direct or indirect support of infantry |
| CFC | Canadian Forestry Corps | units designated to cut down and process trees to provide wood and lumber |
| CGA | Canadian Garrison Artillery | organization responsible for using large-calibre guns against heavily fortified positions |
| CGH | Canadian General Hospital | permanent hospital where extensive treatment was given to the wounded |
| CGR | Canadian Garrison Regiment | unit of 13 battalions formed in April 1918 to perform garrison duty in Canada’s 13 military districts |
| CL | Casualty List | list of soldiers wounded, killed, missing or taken prisoner by the enemy |
| CLH | Canadian Light Horse | cavalry unit, originally intended as a scouting force |
| CMGC | Canadian Machine Gun Corps | soldiers with machine guns responsible for supporting or defending against infantry attack |
| CMR | Canadian Mounted Rifles | mounted soldiers originally, later used largely as infantry |
| C of I | Court of Inquiry | group of officers convened to investigate specific questions or events |
| Com | Command | unit under the command of one officer or non-commissioned officer |
| CO | Commanding Officer | any officer in command of a specific unit (usually battalion level and up) |
| Conv | Convalescent | a soldier recovering from wounds or illness |
| CORD | Central Ontario Regimental Depot | facility in England used to assemble men and to store and administer equipment and materials |
| Coy | Company | unit of approximately 200 men, divided into 4 platoons |
| CRCR | Canadian Reserve Cavalry Regiment | cavalry reserve unit based in England |
| CRT | Canadian Railway Troops | men recruited and organized to operate railways in rear areas |
| CSM | Company Sergeant-Major | senior non-commissioned officer in a company |
| DAC | Divisional Ammunition Company | organization responsible for supplying ammunition to a division |
| DCM | Distinguished Conduct Medal | medal for bravery awarded to other ranks (non-officers) |
| dis | discharged | released from the military service, or from a hospital |
| Div | Division | unit of approximately 12,000 men commanded by a major-general |
| DO | Daily Order (of a unit) | administration orders issued to mark personnel changes of a unit (transfers, hospitalizations, etc.) |
| D of W | Died of Wounds | official cause of death |
| Dvr | Driver | designation or rank of a soldier who drives vehicles |
| East Sandling | East Sandling | location of Canadian military training base in Kent, England |
| emb | embarked | went aboard ship for departure overseas; Canada to Britain or Canada to France |
| EORD | Eastern Ontario Regimental Depot | facility in England used to assemble men and to store and administer equipment and materials |
| Frac | Fractured | medical term for a broken bone |
| GC Badge | Good Conduct Badge | award for good conduct during service |
| Gen | General | commanding officer at division or corps level |
| GHQ | General Headquarters | command centre from which corps or army commanders direct the war |
| Gnr | Gunner | lowest rank in the Royal Canadian Artillery (equivalent to private) |
| GSW | Gunshot Wound | wound caused by a bullet |
| GOC | General Officer Commanding | highest ranking general, usually at corps level |
| HMS | His Majesty’s Ship | vessel under the control of the Royal Navy |
| HMT | His Majesty’s Troopship | designated ship carrying troops between Canada and England and England and France |
| Hosp | Hospital | designated location where soldiers receive medical treatment |
| How | Howitzer | an artillery weapon (various calibres) capable of firing shells in a low or high arc |
| HQ | Headquarters | command centre for a military unit in the field (company level and above) |
| inv “wd” | invalided wounded | a soldier transferred away from the front as a result of wounds received in action |
| KIA | Killed in Action | designation of how a soldier died |
| LG (Lon Gaz) | London Gazette | official British government publication of decorations, honours and promotions |
| LMB | Light Mortar Battery | front line unit of light mortars used for direct fire support |
| LSH | Lord Strathcona’s Horse (Royal Canadians) | cavalry unit first established for the South African War |
| M&D | Medals and Decorations | list of theatre medals or decorations received for military service, as well as special citations |
| MC | Military Cross | award given to officers for specific act(s) of bravery, or for meritorious service |
| MD | Military District | (or Depot) designated military administrative areas in Canada (13 in number) |
| MIA | Missing in action | casualty whose whereabouts and status (alive, dead or captured) after an action are unknown |
| MID | Mentioned-in-Despatches | commendation by commanding officer for outstanding or meritorious service |
| Mil | Military | organization responsible for defending a country or for the conduct of a war |
| Miss | missing | location of an individual is unknown |
| MM | Military Medal | medal for bravery awarded to other ranks (non-officers) |
| MRD | Manitoba Regimental Depot | facility behind front used to assemble men and to store and administer equipment and materials |
| NCO | non-commissioned officer | non-commissioned officer |
| NSRD | Nova Scotia Regimental Depot | facility behind front used to assemble men and to store and administer equipment and materials |
| NYD | not yet determined | a medical condition not yet diagnosed |
| OMFC | Overseas Military Forces of Canada | Canadian cabinet ministry that conducted Canadian military affairs in London, England |
| Orpington | Orpington | location of military hospital in Kent, England |
| O.S. | Overseas | all areas outside the territorial waters of North America |
| P&S | Plaque and Scroll (Memorial) | given to the families of soldiers who died during service |
| Pnr | Pioneer | member of a pioneer battalion, used for specialized engineering work in rear areas |
| PPCLI | Princess Patricia’s Canadian Light Infantry | Canadian regiment of experienced soldiers privately established by Hamilton Galt |
| pres | presumed | official term not available |
| Proc | proceeded | official term not available |
| Pte | Private | lowest rank of enlisted soldier |
| Pt. II O | Part II Orders | administrative orders issued by a unit (see DO) |
| PUO | Pyrexia | of unknown origin fever of an undetermined cause |
| QRD | Quebec Regimental Depot | facility in England used to assemble men and to store and administer equipment and materials |
| RAF | Royal Air Force British | air force (Royal Flying Corps [RFC] before April 1918) |
| RCD | Royal Canadian Dragoons | heavy cavalry unit |
| RCHA | Royal Canadian Horse Artillery | specific regiment of artillery inside the Royal Canadian Artillery |
| RCR | Royal Canadian Regiment | one of the oldest Canadian infantry regiments, founded in 1883 |
| rem | remained | stayed in an area, or stayed on duty |
| Res | Reserve | force of men remaining behind the lines to reinforce the front lines where needed |
| RFB | Reported from Base | unit base report about a soldier |
| RFC | Royal Flying Corps | see RAF |
| RSM | Regimental Sergeant-Major | senior non-commissioned officer in a regiment |
| RTC | Returned to Corps | a soldier returning to duty |
| RTU | Returned to Unit | a soldier returning to a unit following illness, wounds, leave or training |
| Salisbury | Salisbury | location of first Canadian military training base in Southwest England in 1915 |
| Seaford | Seaford | location of Canadian military training base in Sussex, England |
| SEF | Siberian Expeditionary Force | small international force sent to Russia in 1918 to help anti-communist forces |
| Shorncliffe | Shorncliffe | location of Canadian military training base in Kent, England |
| SOS | Struck off strength (of a unit) | when a soldier ceases to be a member of a unit because of transfer, injury or death |
| Spr | Sapper | lowest enlisted rank in Canadian Engineers (see CE) |
| SS | Steamship | transport vessel used to carry troops and equipment |
| Staty | Stationary (Hospital) | large movable hospital of between 400 and 1,000 beds |
| SW | Shrapnel (Shell) | wound type of wound received from shrapnel or shell fragment |
| TMB | Trench Mortar Battery | small- to medium-calibre mortars used in infantry support and to shell enemy trenches |
| TOS | Taken on strength (of a unit) | entry of a soldier to a unit |
| Tpr | Trooper | lowest rank in a cavalry unit |
| trans | transferred | to be sent from one unit or location to another |
| unk | unknown | location of a soldier is not known |
| Wilton | Wilton | location of Canadian military training base in Wiltshire, England (on Salisbury Plain) |
| w, (w) | wounded | injury caused by enemy action |