Your essential guide to acronyms in Line of Duty

Posted in Blog, Television


Anti-corruption unit 12, where our heroes work to root out bent coppers within Central Police force. We’ve also encountered AC-3 and AC-9 in previous series.


Authorised firearms officer. A police officer who has been selected, trained and accredited by their superiors to carry a firearm operationally.


Automatic numberplate recognition. As a car passes an ANPR camera, its licence plate is read and instantly checked against a database of vehicles of interest.


Armed response unit, like the squad headed by Sgt Danny Waldron (Daniel Mays) in series three.


Armed response vehicle, crewed by AFOs to attend incidents believed to involve firearms or other high-risk scenarios. ARVs are adapted and modified to carry specialist equipment.


Breaking and entering. Two crucial elements of the crime of burglary.

Big red key

Manual 16kg steel battering ram for gaining entry to premises. It’s big, it’s red and it opens doors. Also known as “the enforcer”, “the donker” or “the bosher”.


The accidental shooting or injury of a police officer by a colleague.

Bystander triple 9

A 999 emergency call from a civilian.


Covert human intelligence source, aka a police informant/snitch/snout/rat/nark/grass. May meet a violent end when exposed, hence the phrase “snitches get stitches”.


Criminal Investigation Department. Often nicknamed the “brains department” by uniformed officers


Covert operations manager, who runs undercover officers.


Crown Prosecution Service. The independent agency which prosecutes criminal cases that have been investigated by the police and other law-enforcement organisations in England and Wales.


Digital interview recording. Device used to record police interviews, replacing the tapes of old. Look out for the long beep at the beginning of each interrogation.


Directorate of Professional Standards. The internal Metropolitan Police body responsible for investigating complaints against the conduct of its officers.

Farenheit order

Line of Duty’s shoot-to-kill command. Different police operations use different codewords.


Forensic investigator, like Tim Ifield (Jason Watkins) in series four. Gathers and preserves physical evidence at a crime scene to take back to the lab for analysis.


Family liaison officer. Works closely with those affected by serious crimes, such as families of murder victims.


Forensic Medical Examiner or Force Medical Examiner. Any qualified doctor used by UK police to treat injuries, take blood samples or confirm and certify a sudden death.

Furry Exocet

A police dog. Can also be termed a “land shark”.


Gunshot residue. Fragments or particles deposited on the hands and clothes of someone who discharges a firearm.


Gunshot wound. GSWs can be variously classified as moderate, severe or critical.

Hard contact technique

Also known as a contact shot. Where the muzzle of the firearm is pressed against the target’s body or head before discharging. Often the result of close range gunfights or execution-style killings.

IP address

Internet protocol address, a numerical label assigned to every device connected to an online computer network. It may mean a computer’s location or user may be traced.


Immediate response, often heard in the radio call “request IR”. Can also mean incident report.


A missing person. DI Lindsay Denton and an undercover DI Kate Fleming (Vicky McClure) worked for the Missing Persons Unit in series two.


Murder Investigation Team. The specialised homicide squad where DCI Joanne Davidson (Kelly Macdonald) is working in series six.


Management of police information. In series five, a MoPI notice blocked access to DS John Corbett’s records to minimise risk of his cover being blown.


Organised crime group, like the balaclava-clad gangs seen throughout Line of Duty. Civilian members and corrupt police officers work together to plan and conduct large-scale serious crime on a continuing basis.


Observation post or observation point. A position from which to conduct surveillance. Observation may be abbreviated to “obs” or “obbo”.


The police national computer, a database used by law enforcement organisations across the UK.

Reg 15

A regulation 15 or “yellow notice”, advising an officer that a complaint has been made or a conduct matter has come to light which warrants an investigation. This might escalate into “red notice”, terminating their employment.


The Regulation of Investigatory Powers Act 2000. A parliamentary act which regulates the powers of public bodies to carry out surveillance and intercept communications.


Road traffic collision or car crash. Used to be termed an RTA (Road Traffic Accident) until guidelines changed because “accident” implies there’s nobody to blame.


Scene-of-crime officer. A forensic crime scene examiner trained to take photographs of evidence and identify traces left at crime scenes.


Strategic firearms commander, who has overall strategic control of armed operations, with responsibility and accountability for directions given.


Senior investigating officer leading a major case such as murder.


A situation report. A periodic account of the operation’s current status. The term was first popularised by the military during the Second World War.

Status zero

Coded radio call issued by officers who need urgent assistance, often when they’re under attack or their lives are in immediate danger.

Status five

Radio code for an officer being en route to the scene of an incident.

Status six

Radio code for the officer having arrived on the incident scene.


Tactical firearms commander, who sets the working strategy during an armed operation and advises on the deployment of AFOs until the SFC arrives on the scene.


Taking without owner’s consent. Usually applied to the illegal removal of a vehicle.


Undercover operator, such as DI Kate Fleming in series one to three or DS John Corbett in series five. They will often wear civilian clothes or behave in a criminal manner to “fit in” and avoid identification as a law enforcement officer.