Line of Duty acronyms explained - including CHIS and DIR

What do all the technical terms mean?

Author: Alex RossPublished 12th Feb 2024

The brilliant sixth series of Jed Mercurio's Line of Duty came to an end in May 2021, leaving viewers desperately waiting for a seventh series. However, when watching the hit show, many of us have asked the same question.... What do all the technical terms mean?

With AC-12 officers Superintendent Ted Hastings and DI Steve Arnott, and DC Chloe Bishop and DCI Joanne Davidson all using a number of technical terms during the show, many viewers are often left wondering just what they are all talking about!

What on earth do things like OCG and AFO mean?! Well, luckily for us, the BBC have released a detailed description of all the technical terms, so now we can all enjoy Line of Duty like we are one of the AC-12 officers.

Line of Duty: What do the acronyms mean?

OCG - Organised Crime Group: Serious crime planned, coordinated and conducted by people working together on a continuing basis, mostly acting in different roles depending on their skills and expertise.

PACE - Police and Criminal Evidence Act: Established in 1984, a code of practice that regulates police powers and protects public rights.

REG 15 - Regulation 15 notice: A notice that advises an officer that a complaint has been made or a conduct matter has come to light that warrants investigation by professional standards department.

RIPA - Regulation of Investigatory Powers Act 2000: An act of Parliament of the United Kingdom, which regulates the powers of the public bodies to carry out surveillance and investigation, and covers the interception of communications.

RTC - Road Traffic Collision

ANPR - Automatic Number Plate Recognition: Technology is used to detect, deter and disrupt criminality at a local, force, regional and national level.

AC-12 - Anti-Corruption Unit 12: A dedicated unit that holds responsibility for investigating corruption within the police force.

CHIS - Covert Human Intelligence Source: A person who establishes or maintains a personal or other relationship with another person for the covert purpose.

AFO - Authorised Firearms Officer: A police office, who has been selected, trained, accredited and authorised by their chief officer to carry a firearm operationally.

ARVs - Armed Response Vehicles: ARVs are crewed by Authorised Firearms Officers to respond to incidents believed to involve firearms or other high-risk situations.

DIR - Digital Interview Recording: Digital device used to record police interviews.

IOPC - Independent Office for Police Conduct: A non-departmental public body in England and Wales which, since 8 January 2018, is responsible for overseeing the system for handling complaints made against forces in England and Wales.

FI - Forensic Investigator: The FI gathers and preserves physical evidence at a crime scene to take to a lab where they examine what they or other law enforcement personal have found.

I.P. Address - Internet Protocol Address: A numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.

SFC - Strategic Firearms Commander: The SFC has overall strategic command of firearms operations, with responsibility and accountability for directions given.

UCO - Undercover Operative: A method use by law enforcement and intelligence agencies. They wear civilian clothes that fit in to avoid detection.


TFC - Tactical Firearms Officer: A TFC provides guidance on the appropriate use in respect of different tactical options involving the deployment of AFOs.

VPN - Virtual Private Network: The extension of a private network that includes links across shared or public networks, such as the Internet.

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