Question: How many assistant referees assist the Association football referee?
About the article "Association football", section "Players, equipment, and officials".

Candidate passages:
The term referee originated in association football.
Originally the team captains would consult with each other in order to resolve any dispute on the pitch.
Eventually this role was delegated to an "umpire".
Each team would bring their own partisan umpire allowing the team captains to concentrate on the game.
Later, the referee, a third "neutral" official was added, this "referee" would be "referred to" if the umpires could not resolve a dispute.
The referee did not take his place on the pitch until 1891, when the umpires became linesmen (now assistant referees).
Today, in many amateur football matches, each side will still supply their own partisan assistant referees (still commonly called club linesmen) to assist the neutral referee appointed by the governing football association if one or both assistant referees are not provided.
In this case, the role of the linesmen is limited to indicating out of play and cannot decide off side. 
The touch judges and assistant referees cannot stop play, but can signal the referee to enable them to assist the referee. 
FIFA member countries are invited annually to nominate male and female officials for association football, futsal and beach soccer.
Each country's Referee's Committee selects the referees to be nominated to FIFA.FIFA maintains five lists in total: men's and women's association football referees, men's and women's futsal referees, and a single list of beach soccer referees.
Officials in the association football lists are nominated as either referees or assistant referees.
Futsal and beach soccer at international level are usually controlled by two on-field referees and there is no equivalent of the assistant referee. 
Law 6 of the Laws of the Game specifies that "two assistant referees may be appointed".
It also outlines the general duties of the assistant referees; however, their duties in a given game remain subject to the decision of the referee.
These duties usually include indicating:  when the whole ball has passed outside the field of play  which side is entitled to return the ball into the field of play  when a player may be penalised for an offside offence  when a substitution is being requested, or assisting the fourth official (if present) in doing the same  when offences or other infringements of the Laws of the Game have been committed of which the referee does not have an adequate view All decisions by the assistant referees are only advisory to the referee; assistants do not make binding decisions.
An assistant referee may also be called upon by the referee to provide an opinion regarding matters which the referee requires clarification on.
Occasionally the assistant referee will assist in player management during free kicks, as well as provide visual assistance during penalty kicks.
The assistant referees also usually assist the referee with preparatory and administrative functions.
Assistant referees wear a uniform identical to that of the referee and carry brightly-colored flags (usually red, yellow, or some pattern involving those colors) which are used to indicate their decisions to the referee, players, and spectators.
During the game each assistant referee oversees one touch-line and one end of the field utilising the diagonal system of control.
The more senior of the two assistants will normally occupy the side of the field containing the technical areas, to help oversee substitutions.
At higher levels of play, the assistant referees' flags may be equipped with buttons that the assistant referee may press to send an audible signal to the referee in order to get the referee's attention.
Also at the highest levels of play, particularly in matches held in large stadiums, the entire officiating crew may be equipped with wireless microphones and earpieces to facilitate vocal communication across long distances or through loud stadium noise.
Assistant referees were formerly called linesmen.
In 1996, the name was changed, primarily to better reflect the modern role of these officials, and secondarily to become non-gender specific.
They are also sometimes incorrectly referred to as "referee's assistants".
However the term "linesman" is still commonly used, including at lower levels of play where, if the match governing body does not appoint assistant referees to a match, a referee may be empowered to appoint volunteer "club linesmen" who may usually only assist the referee in judging whether the ball has left the field of play. 
On 20 December 2011, UEFA named twelve referees and four fourth officials for Euro 2012.
On 27 March 2012, UEFA issued the full list of 80 referees to be used in Euro 2012, including the assistant referees, the additional assistant referees, and the four reserve assistant referees.
Each refereeing team consisted of five match officials from the same country: one main referee, two assistant referees, and two additional assistant referees.
All of the main referees, additional assistant referees, and fourth officials were FIFA referees, and the assistant referees (including the four reserve assistant referees) were FIFA assistant referees.
For each refereeing team, a third assistant referee from each country was named to remain on standby until the start of the tournament to take the place of a colleague if required.
In two cases, for the French and Slovenian refereeing teams, the standby assistant referees took the place of one of the assistant referees before the start of the tournament.
Continuing the experiments carried out in the UEFA Champions League and UEFA Europa League, the two additional assistant referees were used on the goal line for the first time in European Championship history with approval from the International Football Association Board.
Final referee; only referee assigned to four matches.
Four match officials, who served only as fourth officials, and four reserve assistant referees were also named: