Request stop
Encyclopedia
In public transport
, a request stop or flag stop describes a stopping point at which trains or buses stop only on an as-need or request basis; that is, only if there are passengers to be picked up or dropped off. In this way, infrequently used stopping points can be served efficiently.
Trains save fuel
by continuing through a station when there is no need to stop. There is not a significant saving on time, because trains going through a request stop need to slow down enough to be able to stop if there are passengers waiting. Regardless, significant time savings might cause timetabling problems.
, a request stop, flag stop or whistle stop describes a station
at which trains stop only on an as-needed basis, that is, only if there are passengers to be picked up or dropped off. At request stops for which there are no passengers to be dropped off, trains need only slow in the vicinity of the platform — or, in some cases, pass it at speed — instead of coming to a complete stop at an empty platform. In this way, lightly used stations can remain open and be served efficiently, rather than be closed.
The methods by which trains are notified that there are passengers waiting to be picked up at a request stop vary by station and country:
In the United Kingdom
, most request stop stations require that the guard be informed by passengers wishing to stop at the station and that passengers waiting to catch the train merely make themselves clearly visible to the driver as the train approaches at a speed slow enough to stop if necessary. In some cases the station platform is observable by railway staff either near the station (e.g. in the signal box
at Kidwelly railway station
) or at the station itself. In these latter cases the staff may inform the driver in advance so that there is no need for the train to slow down unnecessarily when no passengers are waiting.
, flag stop stations require that passengers have a reservation to embark or disembark at the station. If there are no reservations for such a station, the train will generally pass at speed. Flag stops on Amtrak are rare as of 2010. Examples of flag stops include Tyrone
and Latrobe
in Pennsylvania
, and Alderson
and Thurmond
in West Virginia
.
On two of the Alaska Railroad
routes, passengers may flag trains nearly any place along the route.
In the northern New York metropolitan area
, Metro-North
has three request stops to serve weekend hikers
traveling to and from the city. The Breakneck Ridge
and Manitou
stations along the Hudson Line
serve Hudson Highlands State Park
and other protected area
s near it; the Harlem Line's Appalachian Trail
station is located where that trail crosses the tracks north of Pawling
. While not officially designated as flag stops, train crews normally treat them as such.
The South Shore Line
in northern Indiana
, has a few flag stops at Gary Airport
, Beverly Shores
, and Hudson Lake
. At these stops, boarding passengers must press a button which activates a strobe light visible to the engineer of the train who will make the stop. Alighting passengers must notify the conductor at the previous stop.
's Polar Bear Express
from Cochrane to Moosonee is operated as a flag-stop route. There are some flag-stop points on Via Rail
route; one example is the Sayabec railway station
in Quebec
. Via Rail also provides flag stop service to a number of communities along its Sudbury – White River train in Northern Ontario
and several of its lines in Western Canada, in addition, passengers on certain routes can disembark at any mile marker on 48 hour notice.
way are request stops, except the termini on both ends.
There are two exceptionals
In Asian part and Abhazian service (after border control at Tshandrypsh station to Suhum city) unofficially may be flagged by passengers nearly any place along the route.
and Switzerland
, request stops sometimes feature an electronic signal
indicator that is operated by the passengers themselves. If a passenger wants the next train to stop, he usually must push a button on the platform changing the signal well before the station. Because these signals are usually well before the station, trains are able to pass at speed if no passenger is waiting. Passengers inside the trains wishing to disembark at a request stop notify the driver by pressing a button inside the train.
Passengers wishing to board the bus at a request stop do so by hailing it with an extended arm as it approaches. Passengers wishing to leave the bus indicate this by using the stop bell or buzzer. Outside of urban areas where there are fewer overlapping routes, it is common for almost all bus stops to be request stops.
Request stops and mandatory stops have different signs in London
. Mandatory stops have the TfL
roundel
symbol in red on a white background with the text "Bus Stop", while request stops have it in white on a red background with the text "Request Stop".
The second type of request stop is also used in the UK, although it is not very common. It is normally referred to as "Hail and Ride
". Passengers signal the driver in the same way as for a fixed request stop anywhere along the route of the bus, regardless of whether there is a fixed stop.
Some bus companies may choose to adopt variations of the above two principal services. For example, in Portland
and Metro Vancouver, people using TriMet
or TransLink
at night can ask a bus driver to drop them off, but can not flag or request a bus driver to pick them up, even if they are in a safe boarding area. In York Region, Ontario
, Strathcona County, near Edmonton
, Alberta
, passengers can use a "dial-a-ride" service by dialing a dispatcher one hour in advance of their journey and telling the dispatcher their name and location. The dispatcher will then tell the next available bus to go to that location and will also tell the requesting person the next bus that will pick them up. The Toronto Transit Commission
offers night request stops to female riders after sunset, and to all riders who express a dire need during the day.
, passengers wishing to board a bus at a bus stop do so by hailing it with an extended arm as it approaches. Passengers wishing to leave the bus indicate this by using the stop bell or buzzer. Almost all bus stops are request stops, except for a few bus stops along downsloping roads which are designated by a bus operator as a mandatory stop, where all buses of that operator have to stop.
signal. The many islands of the Stockholm archipelago
are an example of this.
Public transport
Public transport is a shared passenger transportation service which is available for use by the general public, as distinct from modes such as taxicab, car pooling or hired buses which are not shared by strangers without private arrangement.Public transport modes include buses, trolleybuses, trams...
, a request stop or flag stop describes a stopping point at which trains or buses stop only on an as-need or request basis; that is, only if there are passengers to be picked up or dropped off. In this way, infrequently used stopping points can be served efficiently.
Trains save fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
by continuing through a station when there is no need to stop. There is not a significant saving on time, because trains going through a request stop need to slow down enough to be able to stop if there are passengers waiting. Regardless, significant time savings might cause timetabling problems.
Rail transport
In rail transportRail transport
Rail transport is a means of conveyance of passengers and goods by way of wheeled vehicles running on rail tracks. In contrast to road transport, where vehicles merely run on a prepared surface, rail vehicles are also directionally guided by the tracks they run on...
, a request stop, flag stop or whistle stop describes a station
Train station
A train station, also called a railroad station or railway station and often shortened to just station,"Station" is commonly understood to mean "train station" unless otherwise qualified. This is evident from dictionary entries e.g...
at which trains stop only on an as-needed basis, that is, only if there are passengers to be picked up or dropped off. At request stops for which there are no passengers to be dropped off, trains need only slow in the vicinity of the platform — or, in some cases, pass it at speed — instead of coming to a complete stop at an empty platform. In this way, lightly used stations can remain open and be served efficiently, rather than be closed.
The methods by which trains are notified that there are passengers waiting to be picked up at a request stop vary by station and country:
United Kingdom
Rail transport in Great Britain
The railway system in Great Britain is the oldest in the world, with the world's first locomotive-hauled public railway opening in 1825. As of 2010, it consists of of standard gauge lines , of which are electrified. These lines range from single to double, triple, quadruple track and up to twelve...
, most request stop stations require that the guard be informed by passengers wishing to stop at the station and that passengers waiting to catch the train merely make themselves clearly visible to the driver as the train approaches at a speed slow enough to stop if necessary. In some cases the station platform is observable by railway staff either near the station (e.g. in the signal box
Signal box
On a rail transport system, signalling control is the process by which control is exercised over train movements by way of railway signals and block systems to ensure that trains operate safely, over the correct route and to the proper timetable...
at Kidwelly railway station
Kidwelly railway station
Kidwelly railway station serves the town of Kidwelly , Carmarthenshire. The station is situated on the coast just southwest of Kidwelly itself. Originally the station was the junction of the Burry Port and Gwendraeth Valley Railway...
) or at the station itself. In these latter cases the staff may inform the driver in advance so that there is no need for the train to slow down unnecessarily when no passengers are waiting.
United States
On some lines served by AmtrakAmtrak
The National Railroad Passenger Corporation, doing business as Amtrak , is a government-owned corporation that was organized on May 1, 1971, to provide intercity passenger train service in the United States. "Amtrak" is a portmanteau of the words "America" and "track". It is headquartered at Union...
, flag stop stations require that passengers have a reservation to embark or disembark at the station. If there are no reservations for such a station, the train will generally pass at speed. Flag stops on Amtrak are rare as of 2010. Examples of flag stops include Tyrone
Tyrone (Amtrak station)
Tyrone Station is an Amtrak railway station located approximately 15 miles northeast of Altoona, Pennsylvania on Pennsylvania Avenue south of West 10th Street in Tyrone, Pennsylvania. The station is located in the south end of the borough...
and Latrobe
Latrobe (Amtrak station)
Latrobe Station is an Amtrak rail station located about 40 miles east of Pittsburgh at 329 McKinley Avenue, Latrobe, Pennsylvania. The station is near the center of the city, and is currently served only by Amtrak's Pennsylvanian, which operates once per day in each direction...
in Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
, and Alderson
Alderson (Amtrak station)
Alderson Station is an Amtrak station in Alderson, West Virginia, served by the Cardinal. It is located at 1 C&O Plaza, and functions as a request stop...
and Thurmond
Thurmond (Amtrak station)
Thurmond is an Amtrak station in Thurmond, West Virginia, served by the Cardinal. The station is located on CSX's New River Line.It is one of Amtrak's least-busy stations Thurmond is an Amtrak station in Thurmond, West Virginia, served by the Cardinal. The station is located on CSX's New River...
in West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...
.
On two of the Alaska Railroad
Alaska Railroad
The Alaska Railroad is a Class II railroad which extends from Seward and Whittier, in the south of the state of Alaska, in the United States, to Fairbanks , and beyond to Eielson Air Force Base and Fort Wainwright in the interior of that state...
routes, passengers may flag trains nearly any place along the route.
In the northern New York metropolitan area
New York metropolitan area
The New York metropolitan area, also known as Greater New York, or the Tri-State area, is the region that composes of New York City and the surrounding region...
, Metro-North
Metro-North Railroad
The Metro-North Commuter Railroad , trading as MTA Metro-North Railroad, or, more commonly, Metro-North, is a suburban commuter rail service that is run and managed by the Metropolitan Transportation Authority , an authority of New York State. It is the busiest commuter railroad in the United...
has three request stops to serve weekend hikers
Hiking
Hiking is an outdoor activity which consists of walking in natural environments, often in mountainous or other scenic terrain. People often hike on hiking trails. It is such a popular activity that there are numerous hiking organizations worldwide. The health benefits of different types of hiking...
traveling to and from the city. The Breakneck Ridge
Breakneck Ridge (Metro-North station)
The Breakneck Ridge Metro-North Railroad station serves hikers and campers traveling to and from Breakneck Ridge, north of Cold Spring, New York, via the Hudson Line. Trains stop there on Saturdays, Sundays and holidays only...
and Manitou
Manitou (Metro-North station)
The Manitou Metro-North Railroad station , open part-time serves the residents of that hamlet in the southwestern corner of the Town of Philipstown in Putnam County, New York, via the Metro-North Hudson Line...
stations along the Hudson Line
Hudson Line (Metro-North)
Metro-North Railroad's Hudson Line is a commuter rail line running north from New York City along the east shore of the Hudson River. Metro-North service ends at Poughkeepsie, with Amtrak's Empire Corridor trains continuing north to and beyond Albany...
serve Hudson Highlands State Park
Hudson Highlands State Park
Hudson Highlands State Park is a non-contiguous state park in the U.S. state of New York, located on the east side of the Hudson River. The park runs from Peekskill in Westchester County, through Putnam County, to Beacon in Dutchess County, in the eastern section of the Hudson Highlands.The park's...
and other protected area
Protected area
Protected areas are locations which receive protection because of their recognised natural, ecological and/or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the enabling laws of each country or the regulations of the international...
s near it; the Harlem Line's Appalachian Trail
Appalachian Trail (Metro-North station)
The Appalachian Trail Metro-North Railroad station serves campers and hikers destined for the Appalachian Trail in Dutchess County, New York via the Harlem Line. Trains stop at Appalachian Trail on Saturdays, Sundays, and holidays only. It is the only train station along the 2,175 mile length of...
station is located where that trail crosses the tracks north of Pawling
Pawling (village), New York
Pawling is a village in Dutchess County, New York, USA. The population was 2,233 at the 2000 census. It is part of the Poughkeepsie–Newburgh–Middletown, NY Metropolitan Statistical Area as well as the larger New York–Newark–Bridgeport, NY-NJ-CT-PA Combined Statistical Area...
. While not officially designated as flag stops, train crews normally treat them as such.
The South Shore Line
South Shore Line (NICTD)
The South Shore Line is an electrically powered interurban commuter rail line operated by the Northern Indiana Commuter Transportation District between Millennium Station in downtown Chicago and the South Bend Regional Airport in South Bend, Indiana...
in northern Indiana
Indiana
Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...
, has a few flag stops at Gary Airport
Gary Airport (NICTD)
Gary Airport/Clark Road is a South Shore Line commuter station serving the city of Gary, Indiana. It is one of three NICTD electric train stations in Gary, and serves the Gary/Chicago International Airport, although it does not provide direct access to the airport...
, Beverly Shores
Beverly Shores (NICTD)
Beverly Shores is a station in Beverly Shores, Indiana, called on by South Shore Line trains. The station also serves the nearby Town of Pines....
, and Hudson Lake
Hudson Lake (NICTD)
The Hudson Lake NICTD station is a station stop operated by the South Shore Line in the unincorporated community of Hudson Lake, Indiana. It is one of a very few interurban stations located in a rural region of the United States, being located approximately halfway between the much larger...
. At these stops, boarding passengers must press a button which activates a strobe light visible to the engineer of the train who will make the stop. Alighting passengers must notify the conductor at the previous stop.
Canada
The Ontario Northland RailwayOntario Northland Railway
The Ontario Northland Railway is a Canadian railway operated by the Ontario Northland Transportation Commission, a provincial Crown agency of the government of Ontario....
's Polar Bear Express
Polar Bear Express
The Polar Bear Express is a Canadian passenger train operated by the Ontario Northland Railway in Northern Ontario. Service was introduced in 1964...
from Cochrane to Moosonee is operated as a flag-stop route. There are some flag-stop points on Via Rail
VIA Rail
Via Rail Canada is an independent crown corporation offering intercity passenger rail services in Canada. It is headquartered near Montreal Central Station at 3 Place Ville-Marie in Montreal, Quebec....
route; one example is the Sayabec railway station
Sayabec railway station
The Sayabec railway station is located on Rue Boulay in the village of Sayabec, Quebec, Canada. The station is a flag stop with no ticket service. Sayabec is served by Via Rail's Ocean, and Montreal – Gaspé train...
in Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
. Via Rail also provides flag stop service to a number of communities along its Sudbury – White River train in Northern Ontario
Northern Ontario
Northern Ontario is a region of the Canadian province of Ontario which lies north of Lake Huron , the French River and Lake Nipissing. The region has a land area of 802,000 km2 and constitutes 87% of the land area of Ontario, although it contains only about 6% of the population...
and several of its lines in Western Canada, in addition, passengers on certain routes can disembark at any mile marker on 48 hour notice.
Hong Kong
In Hong Kong, all intermediate stations along the Peak TramPeak Tram
The Peak Tramway is a funicular railway in Hong Kong, which carries both tourists and residents to the upper levels of Hong Kong Island. Running from Central district to Victoria Peak via the Mid-Levels, it provides the most direct route and offers good views over the harbour and skyscrapers of...
way are request stops, except the termini on both ends.
Russian Railways
In Europe part flag stops (nontariff stops) are rare, for example Kuntzevo-2 and 32 km (Domodedovo), but there are many undocumented flag stops that service railway. They are easy.There are two exceptionals
- SVO (terminal DEF) became untariff stop to two pair of local trains (stop assigned instead Lobnya to reduce airport staff delays, all passengers may use the stop)
- Krasnaya ohota (Red hunt) was only the local Petushki-Vladimir stop, assigned lately to all tranis on summer and removed durning reconstruction
In Asian part and Abhazian service (after border control at Tshandrypsh station to Suhum city) unofficially may be flagged by passengers nearly any place along the route.
Austria and Switzerland
In AustriaAustria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
and Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
, request stops sometimes feature an electronic signal
Railway signal
A signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers. The driver interprets the signal's indication and acts accordingly...
indicator that is operated by the passengers themselves. If a passenger wants the next train to stop, he usually must push a button on the platform changing the signal well before the station. Because these signals are usually well before the station, trains are able to pass at speed if no passenger is waiting. Passengers inside the trains wishing to disembark at a request stop notify the driver by pressing a button inside the train.
Bus transport
In bus transport the term request stop is used in two ways:- A fixed bus stopBus stopA bus stop is a designated place where buses stop for passengers to board or leave a bus. These are normally positioned on the highway and are distinct from off-highway facilities such as bus stations. The construction of bus stops tends to reflect the level of usage...
which is only serviced if passengers request it, in a manner similar to a train request stop. - A "Hail and rideHail and rideHail and Ride is a concept in public transport in the United Kingdom. Generally, it refers to boarding or alighting a mode of public transport by signalling the driver or conductor that one wishes to board/alight, rather than the more...
" section of the route where passengers can request the bus be stopped at any point.
United Kingdom
In urban areas, some bus stops are mandatory (i.e., the bus always stops there) while others are request stops. At a stop with many routes, a mandatory stop removes the confusion for passengers when multiple buses arrive within proximity.Passengers wishing to board the bus at a request stop do so by hailing it with an extended arm as it approaches. Passengers wishing to leave the bus indicate this by using the stop bell or buzzer. Outside of urban areas where there are fewer overlapping routes, it is common for almost all bus stops to be request stops.
Request stops and mandatory stops have different signs in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
. Mandatory stops have the TfL
Transport for London
Transport for London is the local government body responsible for most aspects of the transport system in Greater London in England. Its role is to implement the transport strategy and to manage transport services across London...
roundel
Roundel
A roundel in heraldry is a disc; the term is also commonly used to refer to a type of national insignia used on military aircraft, generally circular in shape and usually comprising concentric rings of different colours.-Heraldry:...
symbol in red on a white background with the text "Bus Stop", while request stops have it in white on a red background with the text "Request Stop".
The second type of request stop is also used in the UK, although it is not very common. It is normally referred to as "Hail and Ride
Hail and ride
Hail and Ride is a concept in public transport in the United Kingdom. Generally, it refers to boarding or alighting a mode of public transport by signalling the driver or conductor that one wishes to board/alight, rather than the more...
". Passengers signal the driver in the same way as for a fixed request stop anywhere along the route of the bus, regardless of whether there is a fixed stop.
North America
The term request stop is used on bus networks to describe a stop to let off or pick up passengers that is not at a marked or designated bus stop. This is offered primarily in two different ways:- "night request stop", where bus passengers can request the driver of an evening or night busNight busA night bus service or owl service is a public transport bus service which operates through the night time hours. Many cities operate such services, either in addition to or in substitution for ordinary daytime bus services or rapid transit rail services which may shut for maintenance or due to...
to drop them off or pick them up at a safe place. This is usually allowed to make users feel safer and more comfortable when using the bus. - "flag stop", where bus passengers can request the driver to pick them up (usually by waving or "flagging" their hand at the driver, hence the term "flag stop") and drop them off at safe locations. This practice is usually applied to routes running through rural or suburban areas that would not be effectively served by the traditional practice of waiting at a designated stop.
Some bus companies may choose to adopt variations of the above two principal services. For example, in Portland
Portland, Oregon
Portland is a city located in the Pacific Northwest, near the confluence of the Willamette and Columbia rivers in the U.S. state of Oregon. As of the 2010 Census, it had a population of 583,776, making it the 29th most populous city in the United States...
and Metro Vancouver, people using TriMet
TriMet
TriMet, more formally known as the Tri-County Metropolitan Transportation District of Oregon, is a public agency that operates mass transit in a region that spans most of the Portland metropolitan area in the U.S. state of Oregon...
or TransLink
TransLink (Vancouver)
TransLink is the organization responsible for the regional transportation network of Metro Vancouver in British Columbia, Canada, including public transport and major roads and bridges...
at night can ask a bus driver to drop them off, but can not flag or request a bus driver to pick them up, even if they are in a safe boarding area. In York Region, Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
, Strathcona County, near Edmonton
Edmonton
Edmonton is the capital of the Canadian province of Alberta and is the province's second-largest city. Edmonton is located on the North Saskatchewan River and is the centre of the Edmonton Capital Region, which is surrounded by the central region of the province.The city and its census...
, Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
, passengers can use a "dial-a-ride" service by dialing a dispatcher one hour in advance of their journey and telling the dispatcher their name and location. The dispatcher will then tell the next available bus to go to that location and will also tell the requesting person the next bus that will pick them up. The Toronto Transit Commission
Toronto Transit Commission
-Island Ferry:The ferry service to the Toronto Islands was operated by the TTC from 1927 until 1962, when it was transferred to the Metro Parks and Culture department. Since 1998, the ferry service is run by Toronto Parks and Recreation.-Gray Coach:...
offers night request stops to female riders after sunset, and to all riders who express a dire need during the day.
India
In the state of Andhra Pradesh, APSRTC Request Stop is written on boards in some places. The buses will stop only if people raise their hands visible to the driver.Hong Kong
As in the United KingdomUnited Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, passengers wishing to board a bus at a bus stop do so by hailing it with an extended arm as it approaches. Passengers wishing to leave the bus indicate this by using the stop bell or buzzer. Almost all bus stops are request stops, except for a few bus stops along downsloping roads which are designated by a bus operator as a mandatory stop, where all buses of that operator have to stop.
Taiwan
In Taiwan, on most buses users are required to raise their hand and press a "drop off" button if they want to board or disembark, otherwise the bus will pass the station without stopping.Norway
Along some ferry routes in the fjords in Norway, some stops are equipped with a light that embarking passengers must switch on in order for the ferry to include the stop and pick them up.Sweden
Similar to Norway, commuter ferries are requested to stop by a semaphoreFlag semaphore
Semaphore Flags is the system for conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags; it is read when the flag is in a fixed position...
signal. The many islands of the Stockholm archipelago
Stockholm archipelago
The Stockholm archipelago is the largest archipelago of Sweden, and one of the largest archipelagos of the Baltic Sea.-Geography:The archipelago extends from Stockholm roughly 60 kilometers to the east...
are an example of this.