What Is a CHIS? A Handy Glossary to ‘Line of Duty’ Police Slang, Jargon and Acronyms

© BBC The new series is as incomprehensible as ever. Here’s your crib sheet

You’ve got roughly three seconds – two of which are a phone ringing – in the new series of Line of Duty before the acronyms take over, after which the dialogue descends into a stream of brain-melting letters. Confusing police-speak, in which it feels like all vowels are verboten, is a shortcut to convey longer, complicated phrases when time is of the essence. It also thrusts you into the action – these coppers don’t have time to explain themselves, dammit, there’s corruption to uncover.

If it’s any consolation to the confused viewer, it even trips up the actors. At a previous launch event for the series, Martin Compston (DS Steve Arnott) said: “I think Jed [Mercurio, the creator] sometimes just does it to torture you. There was one line that had five acronyms in the space of one sentence. It kind of becomes a wee badge of honour, trying to learn them.”

The first big piece of police jargon in series six belongs to that of the newest guest star, Kelly Macdonald, who plays DCI Joanne Davidson. Her AOC (acronym of choice, we’re coining it) is ‘CHIS’. What is a CHIS, you ask? That would be a ‘covert human intelligence source’, perhaps better known as ‘spy cops’. These are undercover agents who are recruited by the police, but aren’t employed as police officers, who infiltrate everything from terrorist cells to far-right groups. They’ve been instrumental in foiling serious attacks and unmasking county lines drug gangs, but they’re not without controversy. In recent years, women who were duped into sexual relationships by spy cops – in some instances even having children with them – have brought cases for what they see as state-sanctioned rape.

So, that’s one, rather heavy acronym down; just 12 million to go! Here’s a handy crib sheet to work out what the hell they all mean, in the heat of the action:

AC-12 – The Anti-Corruption team number 12, which Hastings heads up, with Fleming and Arnott working beneath him to uncover police corruption.

AIO – all in order

ARU – armed response unit

B&E – breaking and entering

CC – chief constable – the highest ranking officer in the force

CID – Criminal Investigation Department, essentially the plainclothes division

CPS – Crown Prosecution Service, the agency that prosecutes criminals at trial and advises police forces on investigations

DC – detective constable

DCC – deputy chief constable

DCI – detective chief inspector

DCS – detective chief superintendent

Det Supt – detective superintendent

DI – detective inspector

DIR – digital interview recorder

DS – detective sergeant

FARS – fire and rescue service

FC – forensic coordinator

K9 – dog unit

IRV – incident response vehicle

MOE – method of entry

MoPI – Management of Police Information, a code of practice for the collation and use of information launched in the wake of the Ian Huntley murders

MPU – Missing Persons Unit

Obvs/Obbo – observations, a situation or person who is being monitored

OCG – Organised Crime Group, a legal definition for gangs involved in organised crime and the heart of the storyline in Line of Duty

OCU – undercover officer, also crops up a lot in the series

OIC – officer in charge

OP – observation point

PR – police regulations

PNC – Police National Computer, a database used by law enforcement agencies

RTC – road traffic collision

SCG – Serious Crime Group, Scotland’s Unit in charge of homicide investigations

SitRep – situation report

TA/TOA – time of arrival, also see ETA (estimated time of arrival)

Visuals – What’s in sight, or not, for the officers

Line of Duty starts on Sunday 21 March at 9pm on BBC One