This article may be in need of reorganization to comply with Wikipedia's layout guidelines. (December 2012)
A regional variation generally refers to times when a radio station or television station simultaneously broadcasts different programmes, continuity or advertisements to different parts of its coverage area. This may be so as to provide programming specific to a particular region, such as local news or may be so as to allow advertisements to be targeted to a particular area.
Some regional variations are the consequence of a federal style television network or radio network where a local station is part of a larger broadcast network and broadcasts the network's programmes some of the time and its own programming the rest of the time. The latter is therefore sometimes considered a regional variation. Examples of this include the UK's ITV network throughout much of its history, and American network affiliate stations.
Regional variation is also a common term used in British television listings publications, such as magazines and newspapers, to show the different programmes broadcast in different areas of the country.
Regional variations in the United Kingdom
The BBC has traditionally offered regional variations across many of its services. The Home Service and its successor Radio 4 provided regional variations until the late 1970s when Local Radio took over most of these responsibilities. BBC One and the BBC Television Service have provided variations in the English regions throughout most of their history, and continues to do so today (mainly News and current affairs programming). In Scotland, Wales and Northern Ireland, BBC One has to a large degree been operated as a separate television channel, rather than a variant on BBC One as broadcast in England. BBC Two has in the past broadcast variations within the English regions, though now only has variations for each of the Constituent Countries of the United Kingdom. BBC Choice also briefly had regional variations for these areas.
ITV was originally established as a network of some 14 separate companies, each designated a region of coverage (see History of ITV). Each company provided a mixture of local programming for its own coverage area, as well as airing nationwide networked programmes (usually produced by one of the contractors). ITV has traditionally included more regional variations than the BBC, though since consolidation and majority ownership by ITV plc regional variations on the network are far fewer, and often no more than the minimum requirements as set by Ofcom.
Channel 4 and Channel Five provide no regional variations for programming or continuity, but offer variation during advertising breaks. S4C provided an alternative to Channel 4 in Wales, and broadcasts some of Channel 4's programmes, both simultaneously and slightly behind; though this is technically not a regional variation, rather a separate station in its own right, it is nonetheless frequently described under the heading of 'regional variations' in many newspapers and magazines. In 2009, S4C ceased from broadcasting Channel 4 programmes altogether when analogue television transmitters in Wales were switched off as part of the United Kingdom-wide Digital switchover.
Sky News and Sky1 also provide a variant of their stations for the Republic of Ireland, although specific Sky News coverage for the Republic of Ireland is extremely limited, due in part to the channel with Irish content closing on 3 November 2006, and Sky1's variant is purely an advertising opt-out.
Variations in image and continuity in the UK
Until 2002, ITV's continuity was largely separate in each region of the country, even when announcing broadcasts that were the same throughout the country. The logo of the regional contractor would typically be displayed instead of, or far more prominently than, any 'ITV' logo, before programmes and during trailers. Separate announcers would also be used.
With the consolidation of many ITV companies throughout the 1990s, continuity was often shared between regions as a cost-cutting measure, with the Granada plc companies sharing a continuity announcer (but with different logos) from the late 1990s until all ITV Plc regions shared the same continuity from 2002 onwards. UTV and STV still continue with separate continuity most of the time, with Channel Television occasionally showing its own pre-recorded continuity in place of the network ITV1 branded material.
The BBC also provided regional continuity during the 1970s, often also for nationally networked programming, but this has been phased out. Regional continuity is used between 6am and 2am provided by BBC Scotland, BBC Wales and BBC Northern Ireland for BBC One and BBC Two, outside these times the channels utilise the main BBC One and BBC Two continuity. In England, BBC One continuity is simply referred to as BBC One on air at all times except preceding local programming where all regions except BBC London use pre-recorded announcements. BBC London utilises the main BBC announcers for its local programmes. BBC Two is a single channel in England so uses national continuity at all times.
Regional variations in listings
Magazines and national newspapers print different editions of their TV listings for different areas – some just for the four British nations of England, Scotland, Wales and Northern Ireland, while others produce separate editions for the regions within England also. For example, the "Radio Times" produces six different editions in total (three of them in the English regions), while its oldest rival "TV Times" now produces only four; newspaper supplements are usually printed in just one edition for the whole of the UK.
A regional variations column shows programmes in areas which differ from those in the main listings columns. Generally, only programming that differs from the main schedule is listed rather than listing the entire schedule of each regional area verbatim, much of which would be identical. It is these programmes that make up regional variations. Sometimes all UK regional variations are listed, generally when only one copy of a publication is made for every area, but often only adjoining regions are listed as variations, as is the case in the "Radio Times".
In English regional and UK-wide editions, the main BBC One or ITV column shows programmes in the London region, with other regions (and nations) in the regional variations column. S4C is also often listed here. In Welsh and Scottish editions, adjoining English regions are usually listed. In Northern Ireland, some services from the Republic of Ireland are often listed as regional variations, although they are not.
Technicalities of regional variations
Traditionally, regional variations depend on a network or service broadcasting over multiple transmitters. Typically a 'network' feed will originate from a central location, such as BBC Television Centre, and be fed to all transmitters. Local offices or regional contractors would then be said to opt out of this feed when they switch to feeding the transmitter(s) with locally originated content and to opt in when returning to a national feed. Opt-ins and opt-outs were often quite noticeable in earlier days for causing the picture distortion such as jumping and rolling as the feed was switched; such effects are still noticeable today, though less obvious.
Whilst the BBC originated its network feed from the same place (Television Centre) ITV in earlier days would originate its feed from the broadcaster which made the programme.
Satellite services such as Sky Digital often offer regional variations by transmitting duplicate feeds of the same station for each region traditionally covered by groups of transmitters as an arguably costly way to provide regional variations within an area covered by the same satellite. Both the BBC and ITV do this, as do Channel 4 and Channel Five for advertisements. The digital set top box will determine which version of the channel to supply based on a list of post codes corresponding to the details on the user's smart card.
Opt-out is a term used in broadcasting when a nation or region splits from the main national output. In the United Kingdom, BBC One Scotland, BBC One Northern Ireland and BBC One Wales often opt out of the main BBC One schedule in favour of locally relevant programming.
In a similar manner, local television newsrooms present regional news following national news bulletins—the practise having been popularised by current affairs programme Nationwide and "Sixty Minutes"—after which they would opt into the national programme again. Opting out was also common throughout telethons, such as Children in Need, where regions separate to transmit local coverage.
The term "opt-out" is a peculiarly British idiom when applied to broadcasting, whilst used to describe the occurrence of regional events in an otherwise national stream the term has fallen into technical mis-use. Of the British broadcasters, really only the BBC ever opts out within the proper technical meaning of the term and only then in its English regions.
An opt-out is the process of a regional entity inserting its output into a tributary of an otherwise complete national broadcast distribution feed, creating a local variation in output.
Being a non-commercial broadcaster, the BBC has no need to play out local commercial spots, thus a regional node will typically only output programme material during the local news. Rather than each region having to control or monitor output that is being relayed from a central source, the region will step back from the network, allowing the central source to directly feed its transmitters. The central source is a national feed, which is complete in itself including all continuity, timing, announcement and programme elements. The region interposes to broadcast its element locally, in place of a programme in the national feed, by bringing itself into the network (cold-opt) in preparation for the start of the regional element (warm-opt). 
Within BBC English Regions, the opt-out usually takes place within equipment located within the region's own central technical area. This is not always the case though; for instance the output from BBC Hull, which feeds the Belmont transmitter, is actually switched at BBC Leeds, and the Channel Islands opt-out occurs at Plymouth of the UK mainland, although the programme content comes from both Plymouth and Jersey. Considerable variation can exist between the signal paths for digital (DTT and DSat) and analogue transmissions, leading to great complexity in the opt-out logic.
Commercial broadcasters such as ITV, Channel 4 (with S4C) and Channel Five distribute their programmes to regions complete with local advertising and regional programme variations. Regional programmes, although they may be produced in a particular region, are sent to a centralised play-out facility as contributions for insertion into the regional broadcast feed. BBC programmes in Scotland, Wales and Northern Ireland are broadcast from their own play-out facilities in Glasgow, Cardiff and Belfast, although receiving live and recorded programmes from London they continuously monitor their own output. Thus they don't actually "opt out".
Regional elements are inserted into the French public broadcaster France 3 (France Régions 3, or FR3 for short) by opting out from a national service broadcast from Paris.
Many programme services on North American cable systems are subject to inserts of regional advertisements inserted by the local cable operator.
- The terms "cold-opt" and "warm-opt" are not the generally used BBC terms which are "hard-opt" and "soft-opt" – care needs to be taken with these terms, as the normal IT conventions of hard and soft are reversed within colloquial BBC lexicon.