Rules of squash

Rules of squash

Master the basic rules of squash below. Looking for the full rules? Download the single rules and double rules.

• Full singles rules (PDF)
• Full doubles rules (PDF)

Squash equipment

Squash is played between two players on a squash court each using a standard racket, and a ball approved by England Squash.

2. The Scoring
A match is the best of 3 or 5 games. 
Each game is played to 11 points. The player who scores 11 points first wins the game except that if the score reaches 10-all, the game continues until one player leads by two points. 
Either player may score points (PAR – point–a–rally). The server, on winning a rally, scores a point and retains the service; the receiver, on winning a rally, scores a point and becomes the server.
3. The Warm Up
Before the start of a match, the two players are allowed up to 5 minutes (2½ minutes on each side) to “warm-up” themselves and the ball on the match court. When a ball has been changed during a match, or if the match has been resumed after some delay, the players warm-up the ball to playing condition. 
The ball may be warmed up by either player during any interval in the match.
4. The Service
4.1 Play commences with a service. The player to serve first is decided by the spin of a racket. Thereafter, the server continues serving until losing a rally, when the opponent becomes the server and the server becomes "hand out". 
The player who wins the preceding game serves first in the next game. 
At the beginning of each game and when the service changes from one player to the other, the server can serve from either service box. After winning a rally the server then continues serving from the alternate box. 
To serve a player stands with at least part of one foot on the floor within the service box. For a service to be good, it is served directly onto the front wall above the service line and below the out line so that on its return, unless volleyed, it reaches the floor within the back quarter of the court opposite to the server's box.
6. Good Return
A return is good if the ball, before it has bounced twice on the floor, is returned correctly by the striker onto the front wall above the tin and below the out line, without first touching the floor. The ball may hit the side walls and/or the back wall before reaching the front wall. 
A return is not good if it is “NOT UP” (ball struck after bouncing more than once on the floor, or not struck correctly, or a double hit); “DOWN” (the ball after being struck, hits the floor before the front wall or hits the tin) or “OUT” (the ball hits a wall on or above the out line).
7. Continuity Of Play
Play is expected to be continuous in each game once a player has started serving. There should be no delay between the end of one rally and the start of the next one. 
In between all games an interval of 90 seconds is permitted. 
Players are permitted to change items of clothing or equipment if necessary.
8. Rallies
After a good service has been delivered the players hit the ball in turn until one fails to make a good return. 
A rally consists of a service and a number of good returns. A player wins a rally if the opponent fails to make a good service or return of the ball or if, before the player has attempted to hit the ball, it touches the opponent (including racket or clothing) when the opponent is the non-striker. 
NOTE: AT ANY TIME DURING A RALLY A PLAYER SHOULD NOT STRIKE THE BALL IF THERE IS A DANGER OF HITTING THE OPPONENT WITH THE BALL OR RACKET. IN SUCH CASES PLAY STOPS AND THE RALLY IS EITHER PLAYED AGAIN (“A LET”) OR THE OPPONENT IS PENALISED.
9. Hitting An Opponent With The Ball
If a player strikes the ball, which, before reaching the front wall, hits the opponent, or the opponent’s racket or clothing, play stops. 
If the return would have been good and the ball would have struck the front wall without first touching any other wall, the striker wins the rally, provided the striker did not “turn”.
If the ball either had struck, or would have struck, any other wall and the return would have been good, a let is played.
If the return would not have been good, the striker loses the rally.
9. Turning
If the striker has either followed the ball round, or allowed it to pass around him or her - in either case striking the ball to the right of the body after the ball had passed to the left (or vice-versa) - then the striker has “TURNED”. 
If the opponent is struck by the ball after the striker has turned, the rally is awarded to the opponent. 
If the striker, while turning, stops play for fear of striking the opponent, then a let is played. This is the recommended course of action in situations where a player wants to turn but is unsure of the opponent’s position.
10. Further Attempts
A player, after attempting to strike the ball and missing, may make a further attempt to return the ball. 
If a further attempt would have resulted in a good return, but the ball hits the opponent, a let is played.
If the return would not have been good, the striker loses the rally.
12. Interference
When it is his or her turn to play the ball, a player is entitled to freedom from interference by the opponent. 
To avoid interference, the opponent must try to provide the player with unobstructed direct access to the ball, a fair view of the ball, space to complete a swing at the ball and freedom to play the ball directly to any part of the front wall. 
A player, finding the opponent interfering with the play, can accept the interference and play on, or stop play. It is preferable to stop play if there is a possibility of colliding with the opponent, or of hitting him or her with racket or ball. 
When play has stopped as a result of interference the general guidelines are: 
The player is entitled to a let if he or she could have returned the ball and the opponent has made every effort to avoid the interference.
The player is not entitled to a let (i.e. loses the rally) if he or she could not have returned the ball, or accepts the interference and plays on, or the interference was so minimal that the player’s access to and strike at the ball was not affected.
The player is entitled to a stroke (i.e. wins the rally) if the opponent did not make every effort to avoid the interference, or if the player would have hit a winning return, or if the player would have struck the opponent with the ball going directly to the front wall.
13. Lets
A let is an undecided rally. The rally does not count and the server serves again from the same box. 
In addition to lets allowed as indicated in the paragraphs above, lets can be allowed in other circumstances. For example, a let may be allowed if the ball in play touches any article lying on the floor, or if the striker refrains from hitting the ball owing to a reasonable fear of injuring the opponent. 
A let must be allowed if the receiver is not ready and does not attempt to return the service, or if the ball breaks during play.
15. Duties Of Players
Rule 15 provides guidelines for players. For example 15.6 states that deliberate distraction is not allowed. Players should read this rule in full. 

Some of the 8 sub-sections deal with situations related to matches under the control of officials (Referee/Marker). The use of officials is not covered in this abbreviated version.
16. Bleeding, Injury And Illness
If an injury occurs which involves bleeding, the bleeding must be stopped before the player can continue. A player is allowed a reasonable time to attend to a bleeding wound. 
If the bleeding was caused solely by the opponent’s action, the injured player wins the match. 
If the bleeding recurs no further delay is allowed, except that the player can concede a game, using the 90 second period between games to attend to the wound and stop the bleeding. If unable to stop it, the player must concede the match. 
For an injury not involving bleeding, it must be decided whether the injury was either caused by the opponent or self inflicted or contributed to by both players. 
If caused by the opponent, the injured player wins the match if any recovery time is needed.
If self-inflicted, the injured player is allowed 3 minutes to recover and must then play on, or concede a game using the 90 second rest period between games to recover.
If contributed by both players, the injured player is allowed an hour to recover.
A player who is ill must play on or can take a rest period by conceding a game and using the 90 second interval to recover. Cramps, feeling sick and breathlessness (including asthma) are considered illnesses. If a player vomits on court, the opponent wins the match.
17. Conduct On Court
Offensive, disruptive or intimidating behaviour in squash is not acceptable. 
Included in this category are: audible and visible obscenities, verbal and physical abuse, dissent, abuse of racket, court or ball, unnecessary physical contact, excessive racket swing, unfair warm-up, time-wasting, late back on court, deliberate or dangerous play or action and coaching (except between games).

1. The Game
The game of Singles Squash is played between two players, each using a racket, with a ball and in a court, all three of which meet WSF specifications (see Appendix 5). 
Point-a-Rally Scoring to 11 
Point-a-Rally scoring to 11 points will be the official scoring system for all levels of competitive squash from 1st April 2009. 
Rule 2 THE SCORING is therefore replaced by the following.

2. The Scoring
2.1 Either player may score points. The server, on winning a rally, scores a point and retains the service; the receiver, on winning a rally, scores a point and becomes the server. 
2.2 A match is the best of 3 or 5 games at the option of the organisers of the competition. 
2.3 Each game is played to 11 points. The player who scores 11 points first wins the game except that if the score reaches 10-all, the game continues until one player leads by two points. 
2.4 Each time the score reaches 10-all, the Marker announces “10-all: a player must win by 2 points”. 
2.5The Marker calls "Game ball" to indicate that the player who is leading requires 1 point to win the game in progress, or "Match ball" to indicate that the player who is leading requires 1 point to win the match. This includes the situations where it is the receiver who requires 1 point to win the game or match (e.g. “10-6, game (or match) ball” followed by “hand out, 7- 10, game (or match) ball”.
3. The Warm Up
3.1Immediately preceding the start of play both players shall be allowed onto the court of play for a period of five minutes to warm-up together. After two and a half minutes of the warm-up, the Referee shall call "Half time" and the players shall change sides unless they have already done so. The Referee shall also advise the players when the warm-up period is complete with the call of "Time". 
3.2 In the warm-up both players must have equal opportunities of striking the ball. A player retaining the strike for an unreasonable time is warming up unfairly. The Referee shall decide when the warm-up is unfair and apply Rule 17 
3.3 Either player may warm the ball up during any interval. 
3.4 The players may warm the ball up to playing condition after any interval at the discretion of the Referee.
4. The Service
4.1 Play commences with a service and the spin of a racket decides the right to serve first. Thereafter, the server continues to serve until losing a rally, whereupon the opponent becomes the server and this procedure continues throughout the match. At the commencement of the second and each subsequent game the winner of the previous game serves first. 
4.2At the beginning of each game and each hand the server shall choose from which box to serve and thereafter shall serve from alternate boxes while remaining the server. However, if a rally ends in a let, the server shall serve again from the same box. If the server moves to the wrong box, or either player is uncertain of the correct box for serving, the Marker shall announce the correct box. The Referee shall rule on the correct box if the Marker is uncertain or incorrect, or there is a dispute. 
4.3 To serve, a player shall release the ball from either a hand or the racket and then strike it. Should the player make no attempt to strike it after that release, the player shall release the ball again for that service. 
4.4 A service is good if all the conditions in Rules 4.4.1 - 4.4.5 are met: 
    4.4.1 the server has part of one foot in contact with the floor within the service box without any part of that foot touching the service box line (part of that foot may project over this line if it does not touch the line) at the time of striking the ball; 
    4.4.2 the server, after releasing the ball for service, strikes it correctly on the first or further attempt before the ball falls to the floor, touches a wall, or touches anything the server wears; 
    4.4.3 the server strikes the ball directly onto the front wall between the service and out lines; 
    4.4.4 unless volleyed by the receiver, the first bounce of the ball on the floor is in the quarter court opposite the server's box without touching the short or half court lines; 
    4.4.5 the server does not serve the ball out. 
4.5 A service which does not meet the requirements of Rules 4.4.1 - 4.4.5 is not good and the Marker shall make the appropriate call. The calls are: “foot-fault” for Rule 4.4.1 “not up” for Rule 4.4.2 “fault” for Rule 4.4.3 if the ball strikes a side wall first or the front wall on or below the service line but above the tin “down” for Rule 4.4.3 if the ball strikes the tin or the floor “fault” for Rule 4.4.4 “out” for Rule 4.4.5 A service in which the ball is considered to have struck the front wall and a side wall simultaneously is not good and is called “fault”. 
4.6 The server must not serve until the Marker has completed calling the score. The Marker must call the score without delay. If the server serves or attempts to serve prior to the Marker completing the calling of the score, the Referee shall stop play and require the server to wait until the Marker has completed calling the score.
5. The Play
After the server delivers a good service, the players return the ball alternately until one fails to make a good return, the ball otherwise ceases to be in play in accordance with the rules, a player appeals, or the Marker or Referee makes a call.
6. Good Return
A return is good if all the conditions in Rules 6.1 - 6.3 are met. 
6.1 The striker returns the ball correctly before it has bounced twice on the floor. 
6.2 The ball strikes the front wall above the tin, either directly or via side wall(s) and/or the back wall, without first touching the floor or any part of the striker's body or apparel, or the opponent's racket, body or apparel. 
6.3 The ball is not out or down.
7. Continuity Of Play
After the server delivers the first service, play shall be continuous so far as is practical. However, 
7.1 at any time the Referee may suspend play owing to bad light or other circumstances beyond the control of the players and officials, for such period as the Referee shall decide. The score shall stand. If another court is available and the original court remains unsuitable for play, the Referee may transfer the match to it. 
7.2 There shall be a 90 second interval between the end of the warm-up and the commencement of the first game and between all games. Players may leave the court during these intervals but must be ready to play prior to the expiry of the 90 second interval. 
By mutual consent of the players, play may commence or resume prior to the expiry of the 90 second interval. 
(G1) 

7.3 If a player satisfies the Referee that a change of equipment, clothing or footwear is necessary, the player may leave the court to effect the change as quickly as possible but must do so within 90 seconds. 
7.4 When 15 seconds of a permitted 90 second interval remain the Referee shall call "Fifteen seconds" to advise the players to be ready to resume play. At the end of 90 seconds the Referee shall call "Time". 
It is the responsibility of the players to be in a position to hear the calls of "Fifteen seconds" and "Time". 
Should one or both players not be ready to resume play when “Time” is called, the Referee shall apply Rule 17. 
7.5 If a player is injured, ill or disabled the Referee shall apply Rule 16. 
(G2) 

7.6 The Referee, on deciding that a player has delayed play unreasonably, shall apply Rule 17. 
(G3) 

7.7 If an object, other than a player's racket, falls to the floor of the court while a rally is in progress the requirements are: 
    7.7.1 the Referee, on becoming aware of a fallen object, shall stop play immediately; 
    7.7.2 a player becoming aware of a fallen object may stop play and appeal. 
    7.7.3 If the object falls from a player, that player shall lose the rally, unless Rule 7.7.5 applies or the cause is a collision with the opponent. In the latter case the Referee shall allow a let, unless the player appeals for a let because of interference in which case the Referee shall apply Rule 12 
    7.7.4 If the object falls from a source other than a player, the Referee shall allow a let unless Rule 7.7.5 applies. 
    7.7.5 If the player has already made a winning return when the object falls to the floor, that player shall win the rally. 
    7.7.6 If a dropped object remains unnoticed until the end of the rally, the result of the rally shall stand. 
(G3) 

7.8 If a player drops a racket, the Referee shall allow the rally to continue, unless interference occurred (Rule 12), the ball touched the racket (Rule 13.1.1, distraction occurred (Rule 13.1.3), or the Referee applies a conduct penalty (Rule 17).
8. Winning A Rally
A player wins a rally if: 
8.1 the opponent fails to deliver a good service (Rule 4.4)
8.2 the opponent fails to make a good return (Rule 6), unless the Referee allows a let or awards a stroke to the opponent; 
(G4) 

8.3 the ball touches the opponent (including anything worn or carried), without interference, when the opponent is the non-striker, except as is otherwise provided for in Rules 9 and 10 If interference occurs then the provisions of Rule 12 apply. In all cases the Referee shall make the decision; 
8.4 the Referee awards a stroke to the player as provided for in the Rules.
9. Hitting an opponent with the ball
HITTING AN OPPONENT WITH THE BALL (G4) 
9.1 If the striker hits the ball which, before reaching the front wall, hits the opponent (including anything worn or carried), play shall cease. The Referee, in addition to considering possible infringement of Rule 17 shall assess the ball’s trajectory and shall: 
    9.1.1 award a stroke to the striker if the return would have been good and the ball would have struck the front wall without first touching any other wall, unless Rule 9.1.2 or 9.1.3 applies; (G4 & G5) 
    9.1.2 if the striker turned, award a stroke to the opponent, unless the opponent made a deliberate movement to intercept the return, in which case the Referee shall award the stroke to the striker; 
(G5) 

    9.1.3 if the striker’s return is a further attempt, allow a let, provided that Rule 9.1.2 does not apply; 
    9.1.4 allow a let if the ball either had struck or would have struck any other wall before the front wall and the return would have been good, unless Rule 9.1.5 applies; 
    9.1.5 if deciding the return would have been a winning return, award a stroke to the striker; 
    9.1.6 award a stroke to the opponent if the return would not have been good. 
(G5) 

9.2 If the striker turns: 
    9.2.1 the striker may, before striking the ball, out of fear of hitting the opponent with the ball, stop and appeal. The Referee shall: 
       9.2.1.1 allow a let, if deciding that there was a reasonable fear of the ball hitting the opponent and the striker would have been able to make a good return unless Rule 9.2.3 applies or 
       9.2.1.2 not allow a let, if deciding that the striker could not have made a good return. 
    9.2.2 The striker may, because of interference, stop play and appeal. The Referee shall: 
       9.2.2.1 allow a let, if deciding that the striker is unable to complete an attempt to play the ball because of interference by the opponent or 
       9.2.2.2 award a stroke to the striker, if deciding that the opponent did not make every effort to avoid the interference on turning, or 
       9.2.2.3 not allow a let, if deciding that the striker could not have made a good return regardless of the interference. 
    9.2.3 The Referee shall not allow a let if deciding that the act of turning was to create the opportunity to appeal rather than an attempt to return the ball.
10. Further Attempts to hit the ball
If the striker attempts to strike the ball and misses, the striker may make further attempts.
10.1 If, after being missed, the ball touches the opponent (including anything worn or carried), the Referee shall:
10.1.1 allow a let, if deciding that the striker could otherwise have made a good return, or 
10.1.2 award a stroke to the opponent, if deciding that the striker could not have made a good return.
10.2 The Referee shall allow a let if any such further attempt is successful but results in a good return being prevented from reaching the front wall by hitting the opponent, including anything worn or carried. 
10.3 The striker may, because of interference on the further attempt, stop play and appeal. The Referee shall:
10.3.1 allow a let, if the striker is unable to complete a further attempt to play the ball provided a good return was possible; or 
10.3.2 award a stroke to the striker, if deciding that the opponent did not make every effort to avoid the interference on the further attempt; or 
10.3.3 not allow a let, if deciding that the further attempt would not have resulted in a good return.
11. Appeals
The loser of a rally may appeal against any decision of the Marker affecting that rally. 
A player should preface any appeal under Rule 11 by saying "Appeal please". Play ceases when a player appeals. The Referee, if uncertain of the reason for an appeal, may ask the player for an explanation. 
If the Referee disallows an appeal under Rule 11, the Marker's decision shall stand. If uncertain, the Referee shall allow a let, except where the provisions of Rules 11.2.1, 11.5 or 11.6 apply. 
Appeals and Referee interventions in specific situations are dealt with below (see also Rule 20.4. 
11.1 Appeals on Service. 
    11.1.1 If the Marker makes a call of "Foot-fault", "Fault", "Not up", "Down" or "Out" to the service, the server may appeal. If the Referee upholds the appeal, the Referee shall allow a let. 
    11.1.2 If, after the service, the Marker makes no call, the receiver may appeal, either immediately or at the end of the rally. The Referee, if certain that the service was not good, shall, without waiting for an appeal, stop play and award a stroke to the opponent. In response to an appeal the Referee shall: 
       11.1.2.1 if certain the service was good, award a stroke to the server.
       11.1.2.2 if uncertain, allow a let. 
Appeals on Play other than Service. 
    11.2.1 A player may appeal if the Marker calls "Not up", "Down" or "Out" following that player's return. The Referee, if upholding the appeal or uncertain whether the Marker’s call was correct, shall: 
       11.2.1.1 allow a let, unless Rule 11.2.1.2 or 11.2.1.3 apply; 
       11.2.1.2 award a stroke to the player, if the Marker's call interrupted that player's winning return; 
       11.2.1.3 award a stroke to the opponent, if the Marker's call has interrupted or prevented a winning return by the opponent. 
    11.2.2 If the Marker fails to call "Not up", "Down" or "Out" following a player's return, the opponent may appeal either immediately or at the end of the rally. The Referee, if certain that the return was not good, shall, without waiting for an appeal, stop play and award a stroke to the opponent. In response to an appeal the Referee shall: 
       11.2.2.1 if deciding the return was good, award a stroke to the player; 
       11.2.2.2 if uncertain, allow a let. 
11.3 After the delivery of a service neither player may appeal for anything which occurred before that service, except as Rule 14.3 provides. 
11.4 When the loser makes more than one appeal concerning a rally, the Referee shall consider each appeal. 
11.5 If a player appeals the Marker's call of "Foot-fault", "Fault", "Not up", "Down" or "Out" to a service but that same service subsequently is clearly a fault, not up, down or out, the Referee shall rule only on the subsequent occurrence. 
11.6 If a player appeals the Marker's call of "Not up", "Down" or "Out" to a return but that same return subsequently is clearly down or out, the Referee shall rule only on the subsequent occurrence.
12. Interference
12.1 The player whose turn it is to play the ball is entitled to freedom from interference by the opponent. 
12.2 To avoid interference the opponent must make every effort to provide the player with: 
(G6) 

    12.2.1 unobstructed direct access to the ball after completion of a reasonable follow- through; 
    12.2.2 a fair view of the ball on its rebound from the front wall; 
(G7) 

    12.2.3 freedom to hit the ball with a reasonable swing; 
    12.2.4 freedom to play the ball directly to any part of the front wall. 
12.3 Interference occurs if the opponent fails to fulfil any of the requirements of Rule 12.2, even the opponent makes every effort to fulfil those requirements. 
12.4 A player’s excessive swing can contribute to interference for the opponent when it becomes the latter's turn to play the ball. 
12.5 A player encountering possible interference has the choice of continuing to play or of stopping and appealing to the Referee. 
(G8) 

    12.5.1 A player seeking a let or a stroke should appeal by saying “Let please”. 
(G9 ">G10) 
    12.5.2 Only the player whose turn it is to play the ball may appeal. The player must appeal either immediately the interference occurs or, when clearly not continuing play beyond the point of interference, without undue delay. 
12.6 The Referee shall decide on the appeal and shall announce the decision with the words "No let", "Stroke to (name of player or team)", or "Yes let" (see flowchart in Appendix 4.1). The Referee alone makes all decisions, which are final. The Referee, if uncertain of the reason for an appeal, may ask the player for an explanation. 
12.7 The Referee shall not allow a let and the player shall lose the rally if the Referee decides: 
(G6) 

    12.7.1 there was no interference or the interference was so minimal that the player’s fair view of the ball and freedom to get to and play the ball were not affected; 
(G6) 

    12.7.2 interference occurred but either the player would not have made a good return or the player has not made every effort to get to and play the ball; 
    12.7.3 the player moved past the point of interference and played on; 
(G11) 

    12.7.4 the player created the interference in moving to the ball. 
12.8The Referee shall award a stroke to the player if: 
    12.8.1 there was interference, which the opponent did not make every effort to avoid, and the player would have made a good return; 
(G7) 

    12.8.2 there was interference, which the opponent made every effort to avoid, but the opponent’s position prevented the player’s reasonable swing and the player would have been able to make a good return; 
(G7) 

    12.8.3 there was interference, which the opponent made every effort to avoid, and the player would have made a winning return; 
    12.8.4 the player refrained from hitting the ball which, if hit, would clearly have struck the opponent going directly to the front wall; or to a side wall but in the latter case would have been a winning return (unless in either case turning or further attempt applies). 
12.9 The Referee shall allow a let if there was interference, which the opponent made every effort to avoid, and the player would have made a good return. 
12.10 The Referee shall not award a stroke to a player who causes interference with an excessive swing. 
12.11 The Referee may allow a let under Rule 12.9 or award a stroke under Rule 12.8 without an appeal, if necessary stopping play to do so. 
12.12 The Referee may also apply Rule 17 when interference occurs. The Referee shall, stopping play if it has not already stopped, apply an appropriate penalty if: 
(G12) 

    12.12.1 the player made significant or deliberate physical contact with the opponent; 
    12.12.2 the player endangered the opponent with an excessive swing.
13. Lets
In addition to lets allowed under other rules, the Referee may or shall allow lets in certain other cases. A player should request a let by saying "Let please". The Referee, if uncertain of the reason for an appeal, may ask the player for an explanation. 
13.1 The Referee may allow a let if: 
    13.1.1 the ball in play touches any article lying on the floor (see Rule 15.3; 
(G7) 

    13.1.2 the striker refrains from hitting the ball onto any of the walls including the back wall owing to a reasonable fear of injuring the opponent; 
    13.1.3the Referee determines that an occurrence on or off the court distracted either player. A player appealing for distraction must do so immediately the distraction occurs. Notwithstanding the above the Referee may award a stroke to a player who has been distracted if that player could have played a winning return but for the distraction; 
    13.1.4 the Referee determines that a change in court conditions affected the result of the rally. 
13.2 The Referee shall allow a let if: 
    13.2.1 the receiver is not ready and does not attempt to return the service; 
    13.2.2 the ball breaks during play; 
    13.2.3 the Referee is unable to decide an appeal; 
    13.2.4 a player makes an otherwise good return but either the ball lodges in any part of the playing surface of the court, preventing it from bouncing more than once on the floor, or the ball goes out after its first bounce. 
13.3 If the striker appeals for a let under Rules 13.1.1 to 13.1.4, the Referee shall allow a let only if the striker can make a good return. For a non-striker appeal under Rules 13.1.1, 13.1.3 and 
    13.1.4 this is not a requirement. 
13.4 If the striker attempts to play the ball, the Referee may still allow a let under Rules 13.1.1,13.1.3, 13.1.4 and 13.2.2. 
13.5 The appeals requirements of Rule 13 are: 
    13.5.1 a player’s appeal is necessary for the Referee to allow a let under Rules 13.1.2 (striker only), 13.1.3, 13.2.1 (receiver only) and 13.2.3; 
    13.5.2 a player’s appeal or Referee intervention without appeal is applicable to Rules 13.1.1,13.1.4, 13.2.2 and 13.2.4.
14. The Ball
14.1 At any time, when the ball is not in actual play, either player or the Referee may examine the ball. The Referee may substitute another ball by mutual consent of the players, or on appeal by either player. 
14.2 If a ball breaks during play, the Referee, after confirming it is broken, shall replace it promptly with another ball. 
14.3 If the ball breaks during play without being noticed during the rally, the Referee shall allow a let for the rally in which the ball broke, if the server appeals prior to the next service or if the receiver appeals prior to attempting to return that service. 
(G13) 

    14.3.1 If the receiver appeals prior to attempting to return service and the Referee decides the ball broke during that service, the Referee shall allow a let for that rally only, but if uncertain shall allow a let for the previous rally. 
14.4 The provisions of Rule 14.3 do not apply to the final rally of a game. In that case a player must appeal immediately after the rally. 
14.5 If a player stops during a rally to appeal that the ball is broken, only to find subsequently that the ball is not broken, then that player shall lose the rally. 
14.6 The ball shall remain within the court at all times, unless the Referee permits its removal. 
14.7 When the Referee has substituted another ball or when the players resume a match after some delay, the Referee shall allow the players to warm the ball to playing condition. Play shall then resume on the direction of the Referee, or by mutual consent of the players, whichever is earlier.
15. Duties Of The Players
15.1 The players must observe all the Rules and the spirit of the game. Failure to do so could bring the game into disrepute and Rule 17 may be applied. 
15.2 Players must be ready to commence play at the announced starting time of the match. 
15.3 Players are not permitted to place within the court any object(s), clothing or equipment. 
15.4 Players are not permitted to leave the court during a game without the permission of the Referee. If they do the Referee may apply Rule 17 
15.5 Players are not permitted to request a change of Marker or Referee. 
15.6 A player must not deliberately distract the opponent. If this occurs the Referee shall apply Rule 17 
15.7 Players should preface appeals by saying “Let please” or “Appeal please” according to the circumstances. Pointing with the finger or racket, other gestures, raised eyebrows or other eye activity are not universally recognised methods of appeal. 
15.8 Players must comply with any additional competition regulations (e.g. the clothing requirements of the tournament), as well as those contained in the Rules.
16. Bleeding, Illness, Disability ..
G14 Bleeding, Illness, Disability and injury

16.1 Bleeding: The Referee shall immediately stop play when any player has visible bleeding, an open wound or blood-stained clothing. Before allowing play to continue the Referee shall require that the bleeding be stopped, the wound covered and any blood-stained clothing changed, allowing such time as is reasonable and necessary and is available on the tournament schedule. 
If the bleeding was caused solely by the opponent, the Referee shall immediately award the match to the player. 
    16.1.1 Recurrence of bleeding: If the bleeding recurs, for which recovery time has already been allowed, the Referee shall allow no further recovery time except that the player may concede the game in progress and use the 90 second interval between games for recovery. If the visible bleeding continues at the end of this 90 second interval the player shall concede the match. A player may only concede one game for one 90 second interval. 
If the covering of the bleeding wound falls off or is removed during the match, thereby exposing the wound, the Referee shall consider this to be a recurrence of the bleeding, unless all sign of bleeding has ceased. 
16.2 Illness or Disability: A player suffering illness or disability not involving bleeding has the following options: 
    16.2.1 resuming play without delay; 
    16.2.2 conceding the game in progress, accepting the 90 second interval, or 
    16.2.3 conceding the match. 
Symptoms of tiredness, alleged illness, or disability not reasonably evident to the Referee, or recurrence of pre-existing ailments, including injuries sustained earlier in the match, shall be dealt with under this Rule 16.2. This includes cramps of any kind, actual or impending nausea and breathlessness, including asthma. The Referee shall inform the players of the decision and the requirements of the rules. 
16.3 Injury: 
    16.3.1If a player claims that an injury has occurred, the Referee must be satisfied that the injury is genuine and, if so, decide the category of injury, informing the players of the decision and of the requirements of the rules. The player is only entitled to recovery time immediately after the injury occurred. The categories are: 
       16.3.1.1 self-inflicted, where the opponent did not contribute to the injury; 
       16.3.1.2 contributed, where the opponent accidentally contributed to or accidentally caused the injury. The Referee shall not interpret the words "accidentally contributed to or accidentally caused by" to include the situation where a player is crowding the opponent; 
       16.3.1.3 opponent-inflicted, where the opponent solely caused the injury. 
    16.3.2 If the injury involves bleeding, Rule 16.1 shall apply until the bleeding has stopped. Subsequently Rule 16.3.3 applies. 
    16.3.3 If bleeding is not involved the following rules shall apply: 
       16.3.3.1 for a self-inflicted injury (Rule 16.3.1.1) the Referee shall allow 3 minutes for the injured player to recover. The Referee shall call “Time” at the end of the 3 minute period after giving a 15 second warning. If the player requests additional recovery time beyond 3 minutes, the Referee shall require the injured player to concede one game, accept the 90 second time interval between games and then resume play or concede the match. If the injured player has not returned to the court when “Time” is called, the Referee shall award the match to the opponent; 
       16.3.3.2 for a contributed injury (Rule 16.3.1.2) the Referee shall allow one hour for the injured player to recover and such additional time as the time- schedule of the competition permits. The Referee shall call “Time” at the end of any recovery time allowed. The injured player must, by the end of this period, resume play or concede the match. If the injured player resumes play, the score at the conclusion of the rally in which the injury occurred shall stand; 
       16.3.3.3 for an opponent-inflicted injury (Rule 16.3.1.3) the Referee shall apply Rule 17 and if the injured player requires time to recover, the Referee shall award the match to the injured player. 
16.4 If an injured player, having been granted a period of recovery time, wishes to resume play prior to the expiry of that time, the Referee shall permit the opponent sufficient time to prepare to resume play. 
16.5 If a player claims injury and the Referee is not satisfied that an injury has occurred, the Referee shall require the player to resume play; or concede one game, accept the time interval available and then either resume play or concede the match. 
16.6 If conceding the game, the player shall retain any points already scored and at the conclusion of the 90 second interval between games shall either resume play or concede the match.
17. Conduct On Court
17.1 If the Referee considers that a player’s behaviour is disruptive, intimidating or offensive to the opponent, an official or a spectator, or could in any way bring the game into disrepute, the Referee shall penalise the player. 
(G15) 

17.2 Offences with which the Referee shall deal under this rule include audible and visible obscenities, verbal and physical abuse, dissent to Marker or Referee, abuse of racket, ball or court and coaching, other than during the interval between games. Other offences include significant or deliberate physical contact (Rule 12.12.1, excessive racket swing (Rule 12.4, unfair warm-up (Rule 3.2, late back on court (Rule 7.4, dangerous play or action (Rule 16.3.1.3 and time-wasting (Rule 7.6. 
(G16) 

17.3The Referee shall apply one of the following penalties for these and any other offences. Warning (called a Conduct Warning). Stroke awarded to opponent (called a Conduct Stroke). Game awarded to opponent (called a Conduct Game). Match awarded to opponent (called a Conduct Match). 
    17.3.1 If the Referee stops play to give a Conduct Warning, the Referee shall allow a let. 
    17.3.2 During a rally, if an incident occurs warranting the award of a Conduct Stroke, the Referee shall stop play, if it has not already ceased, and award a stroke. Application of the Conduct Stroke becomes the result of the rally. 
    17.3.3 If the Referee awards a Conduct Stroke as a result of an incident between rallies, the result of the completed rally stands and the Conduct Stroke award is additional to the score but without further change of service box. 
    17.3.4 If the Referee awards a Conduct Game, that game shall be the one in progress or the next game if one is not in progress. In the latter case the interval between games shall not apply. The offending player shall retain any points already scored in the game awarded.
18. Control Of A Match
(G17) 

18.1 A Referee, assisted by a Marker, normally controls a match. Although the Referee may undertake the duties of the Marker as well, the WSF recommends that separate officials carry out the two roles. 
18.2 The correct location for the Referee and Marker is at the centre of the back wall, as close to that wall as possible, above the out line on the back wall and preferably with seating.
19. Duties Of A Marker
(G18) 

19.1 The Marker shall call the play, followed by the score, with the server's score called first. The Marker shall call services and returns which are not good using the recognised calls of "Fault", "Foot-fault", "Not up", "Down", "Out", "Hand-out" and "Stop" (see Appendix 3.1) as appropriate and shall repeat the Referee's decisions. 
19.2 At the end of the rally the Marker shall call the score without delay and after the Referee has decided any appeals. 
19.3 If the Marker makes a call, the rally shall cease. 
19.4 The Marker, if unsighted or uncertain, shall make no call. 
19.5 If play ceases without the Marker having made a call, the Marker, if unsighted or uncertain, shall advise the players and the Referee shall make the relevant decision. If also uncertain, the Referee shall allow a let. 
19.6 The Marker shall keep a written record of the score and the correct side for service.
20. Duties Of A Referee
G19 20.1 The Referee shall rule on all appeals, make decisions where the Rules call for them and shall decide all appeals against the Marker's calls or lack of calls. The decision of the Referee shall be final. 

The Referee must announce all decisions to the players on the court and must make all calls in a voice loud enough to be heard on the court and in the gallery. 
20.2 The Referee shall exercise control: 
    20.2.1 when one of the players appeals, including an appeal against any specification; 
    20.2.2 to ensure that all relevant rules are applied correctly; 
    20.2.3 when the behaviour of any spectator, official, manager or coach is disruptive to the play or offensive to the players, officials or spectators. The Referee shall suspend play until the disruption has ceased and, if necessary, shall require the offending person(s) to leave the court area. 
20.3 The Referee shall not intervene in the Marker's calling of the score unless the Referee decides that the Marker has called the score incorrectly. In that case the Referee shall correct the score and the Marker shall repeat the corrected score. 
20.4 The Referee shall not intervene in the Marker's calling of the play unless the Referee decides that the Marker has made an error in stopping play or allowing play to continue, in which case the Referee shall immediately rule accordingly. 
20.5 The Referee shall enforce all Rules relating to time. 
20.6 The Referee shall keep a written record of the score and the correct side for service. 
20.7 The Referee is responsible for ensuring that court conditions are satisfactory for play. 
20.8 The Referee may award a match to a player whose opponent is not present on court, ready to play, within ten minutes after the announced time of play.
G1 Change of Equipment
In order to prevent one player from gaining an unfair rest interval through a change of equipment, the Referee, before allowing a player to leave the court to make the change, shall be satisfied that there has indeed been a material deterioration of the equipment. 
The preference for another racket, or a different pair of shoes where no physical deterioration is evident, is not sufficient reason for the player to change that equipment. The player may leave the court to effect the change as quickly as possible and must do so within 90 seconds. 
If a player's glasses break or a player loses a contact lens, that player is permitted 90 seconds, after which the player must resume play. 
If a player is unable to resume play because of lack of alternative equipment, the Referee shall award the match to the opponent.
G2 Time-Wasting
Time-wasting is an attempt by one player to gain an unfair advantage over the opponent. Prolonged discussion with the Referee and slow preparation to serve or receive service are examples. The Referee shall apply Rule 17when this occurs. 
While excessive ball-bouncing prior to service is time-wasting, it does not constitute serving the hand out. 
Players should be aware that during the 90 second intervals, the Referee's call of "Fifteen seconds" is advice for them to return to court. A player who is not ready to resume play on the call of "Time" is gaining an unfair advantage and the Referee shall apply Rule 17
G3 Fallen object
Rule 7.7 makes it clear that, if any object falls (or is thrown) to the floor of the court, play must cease. Since an injury may occur if a player treads on any object of significant size or texture, the Referee or Marker shall halt play with the word "Stop", or the player(s) may stop and appeal. If the fallen object is unnoticed by players and Officials until the end of the rally and the Referee judges there has been no effect on the outcome of the rally, the result of the rally shall stand (Rule 7.7.6. 

Players are responsible for retaining their equipment. As a general rule, a player who drops or throws a piece of equipment will lose a stroke. Exceptions are equipment falling as a result of a collision when the Referee may allow a let or award a stroke depending on whether the player has hit a winning return. If the collision results in an appeal for interference, Rule 12 will take precedence. 
If a player drops a racket without colliding with the opponent, the Referee shall allow the rally to continue under most circumstances. It is considered that the player is already at a significant disadvantage, as the player must pick up the racket to remain in the rally. 
The Referee shall deal with a player’s deliberate dropping or throwing of an object to the floor of the court under Rule 17
G4 Player hit by ball including turning ...
Player hit by ball including turning and further attempt
If the ball hits the non-striker the Referee shall make a decision in all cases and the Marker's call is not required until after the Referee has made this decision. 
If the ball, coming from the front wall, hits the non-striker without interference occurring, the non- striker loses a stroke unless further attempt applies (Rule 10. The definition of "Attempt" makes it clear that even a fake swing of the racket or feint at the ball is an attempt, but racket preparation comprising only backswing with no racket movement towards the ball is not an attempt. Rules 9 and 10 cover the various situations in which the ball going to the front wall hits the non-striker. If the ball hits the striker (without interference) the striker loses the rally and the Marker shall call "Not up", because the striker has not struck the ball correctly. The Referee need not make a decision unless the Marker fails to make a call. 
When the ball strikes either player and interference occurred, the Referee shall apply Rule 12 
In deciding to play the ball on turning, a player must ensure that the return will not hit the opponent. If the player does hit the opponent with the ball after turning, the Referee shall award a stroke to the opponent, unless the opponent made a deliberate movement to prevent a good return reaching the front wall, in which case the Referee shall award a stroke to the striker.
G5 Interference on turning ...
Interference on turning or a further attempt
When a player turns or makes a further attempt to play the ball, the opponent still has an obligation to make every effort to provide the player with freedom to sight the ball and to get to and play the ball as provided for in Rule 12 However, the act of turning or of recovering for a further attempt is often so quick that the opponent does not have a reasonable opportunity to clear before the interference occurs. In such cases, the Referee shall allow a let. Conversely, if the opponent had ample time to clear but made no effort to do so, or deliberately moved thereby creating the interference, the Referee shall award a stroke to the player. 
When a player shapes to play the ball on one side and then brings the racket across the body to take the ball on the other side, it is neither turning nor making a further attempt and, if interference occurs, Rule 12 applies. This position frequently occurs after the ball has hit the side wall and the front wall simultaneously and then rebounds into the middle of the court.
G6 Minimal interference ...
Making every effort and minimal interference
The opponent must make every effort to clear the ball after playing a return. The opponent’s route should allow the player unobstructed direct access to the ball, provided the player has not moved in to play the ball so quickly as to block the opponent’s exit. In the latter case the Referee shall allow a let, unless the player could not have made a good return, in which case the Referee shall not allow a let. 
However, it is equally important for the player to make every effort to get to and play the ball. If the player does not make every effort to get to and play the ball, that is a significant factor in the Referee's assessment of whether or not that player could have reached the ball and made a good return. 
The Referee shall decide the degree of effort that the player should make to demonstrate "making every effort". This does not give the player the right to abuse the opponent physically and the Referee shall penalise significant or deliberate physical contact under Rule 12 or Rule 17 
When a player appeals for a let, having encountered some interference, the Referee, when deciding that the interference had no effect on that player’s sighting of the ball and freedom to get to and play the ball, shall not allow a let. This is minimal interference and includes situations in which: the opponent crossed the flight of the ball very early in its trajectory from the front wall but still allowed the player time to sight the ball; the player brushed past the opponent on the way to the ball without affecting the player’s direct access; and the racket swing brushed the opponent, the opponent’s clothing or racket without affecting the racket’s swing. 
However, when interference has occurred, the Referee shall not refuse a let in situations in which the player was clearly making every effort (albeit short of physical contact with the opponent) to get to and play the ball and had demonstrated to the Referee the ability to reach the ball.
G7 Interference with strikers swing ...
Rule 12.2.3 allows the striker “freedom to hit the ball with a reasonable swing”. If the striker stops play because of the opponent not granting this freedom and appeals, the Referee shall consider following options: 

1. If the opponent is too close and has prevented the striker’s reasonable swing and is hit or would have been hit with the racket, the Referee shall award a stroke to the striker. 
2. If the striker stops play as a result of slight racket contact with the opponent, who is making every effort to clear, the Referee shall allow a let. This is different from the minimal interference described in G6. The amount of contact must be sufficient to affect the player’s swing, but insufficient to prevent it. 
3. If the striker stops play for fear of hitting the opponent and the opponent, though close to, does not prevent the striker’s reasonable swing, the Referee shall allow a let under rule 13.1.2 - reasonable fear of injury. As long as the opponent does not prevent a reasonable swing, a let is the appropriate decision. 
4. If the striker stops play for fear of hitting the opponent and the opponent is well clear of the reasonable swing, the Referee shall not allow a let, as the striker has judged the opponent’s position incorrectly.
G8 Method of appeal
The correct method of appeal when interference or Rule 13 instances have occurred is to say "Let please" and for other occurrences under Rule 11 is to say "Appeal please". 
Players sometimes use other forms of appeal including a raised hand or racket, especially when communication between players and Referee is difficult. A Referee accepting any form of appeal other than the standard "Let please” or “Appeal please” must be satisfied that the player is actually making an appeal.
G9 Timing of appeal
The timing of an appeal on interference is important. 
In the case of an appeal concerning fair view and freedom to hit the ball directly to the front wall (commonly known as "crossing the flight"), the Referee shall consider the situation at the time the player could have hit the ball. 
In the case of interference on backswing, the appeal must be immediate and before the player makes any attempt to play the ball. Any attempt to hit the ball after backswing interference has occurred indicates that the striker has accepted the interference and thus forfeits the right of appeal. 
If there is interference in the act of playing the ball, which includes a reasonable backswing, hit and reasonable follow-through, an appeal is justified. The Referee shall consider whether the opponent was crowding and not allowing freedom to play the ball in deciding whether to allow a let or to award a stroke. 
If a player appeals for not being ready to receive service, the Referee shall allow a let, unless deciding the player delayed play unnecessarily. In the latter case the Referee could apply Rule 17
G10 Early appeal
If a player makes an appeal for interference before the result of the opponent’s return is known, this is regarded as an early appeal. If a player makes an early appeal and the opponent’s return subsequently goes down or out, the Referee shall allow the result of the rally to stand, the player winning the rally. 
When the opponent appeals for a let for interference before the player has completed a reasonable follow through, this is also regarded as an early appeal. In this case the opponent has no right of appeal and the Referee shall not award a let.
G11 Created interference
At all times an opponent must allow the player unobstructed direct access to play the ball. 
However, sometimes the situation arises in which the opponent has caused no interference (i.e. the opponent has clearly provided the required direct access) but the player takes an indirect route to the ball which takes the player towards, or very close to, the opponent's position. The player then appeals for a let because of being "obstructed" in access to the ball. 
If there is no genuine reason for this indirect route, the player has created the interference where none otherwise existed and, if the player appeals, the Referee shall not allow a let. Whether the player could make a good return is not a consideration - in order to remain in the rally the player must get to and play the ball. 
This is different from two situations in which a player, in attempting to recover from a position of disadvantage, does not have direct access to the ball. In the first situation the player is "wrong-footed" and anticipates the opponent hitting the ball one way, starts moving that way, but having guessed wrongly, changes direction to find the opponent in the way. In this situation the Referee shall allow the player a let on appeal if the recovery is sufficient to demonstrate the player would have made a good return. In fact, if the opponent prevents the incoming player from playing a winning return, the Referee shall award a stroke to that player. 
Secondly, if a player plays a poor return that gives the opponent a position of advantage, the Referee shall allow the player a let only if, in taking the direct line to the ball for the next return, the Referee determines that, but for the interference, that player would have been able to get to and play the ball.
G12 Significant or deliberate...
Significant or deliberate physical contact is both detrimental to the game and potentially dangerous. In blatant cases the Referee shall stop the rally and award the appropriate penalty. Where the player "pushes off" the opponent and this has no significant effect on the opponent, the Referee shall allow the rally to continue and give a warning to that player at the end of the rally. Where there is a significant effect, the Referee shall stop play and apply Rule 17
G13 Broken ball
When the receiver, without attempting to return the service, appeals that the ball is broken, the Referee will normally allow a let for that rally. However, if the Referee considers that the ball broke in the previous rally, the Referee shall allow a let for the previous rally. This also applies if the service is not good.
G14 Bleeding, illness, disability ..

bleeding, illness, disability or injury 
1. If a player has visible bleeding, the Referee shall require the player to leave the court immediately. The Referee shall not permit play to resume while the bleeding is visible. The Referee shall permit recovery time for bleeding according to Rule 16.1. A player, unable to stop bleeding within the total time the Referee permits, shall either concede one game to gain a further 90 seconds and then continue play without bleeding, or concede the match. 
If an athlete is bleeding and needs attention, then the individual attending to the athlete should wear gloves and make sure he/she washes his/her hands. Similarly, if there has been any contact with the opponent, the area of contact needs to be washed with soap and water. The court should be cleaned of any blood. 
If a player's clothing has become blood-stained as a result of the injury, the player shall change that clothing before resuming play. 
If the bleeding recurs after recovery time has been allowed, the Referee shall allow no further recovery time, except that the player may concede the game in progress and use the interval between games to recover. 
2. A player suffering illness or disability on court has the option, except where blood is visible, of completing the game in progress or of conceding that game or the match. 
A player who does not wish to concede the match, but who requires recovery time or who needs to leave the court, shall concede the game. After informing the Referee, the player shall take the 90 second interval between games for recovery, then be ready to play; or concede the match. The player may concede only one game. 
If a player vomits or otherwise makes the court unplayable, the Referee shall award the match to the opponent, irrespective of whether the sick player is able to resume play (Rule 17). The Referee's decision with regard to court conditions is final. 
In the case of symptoms of tiredness, alleged injuries not reasonably evident to the Referee or pre-existing ailments, the Referee shall not permit recovery time (except that the Referee shall allow the player concerned the option of conceding one game to take the 90 second interval between games and then resume play). Included in this category are cramps, whether abdominal pains or muscle cramps, actual or impending nausea and breathlessness including asthmatic conditions. 
3. If a player is injured the Referee, after confirming that the injury is genuine, shall advise the players of the requirements of the Rules, inform the players of the category of the injury and shall ascertain the player's intentions regarding a resumption of play. 
When a player suffers a self-inflicted injury, i.e. an injury which clearly does not involve the opponent as described in Rule 16.3.1.1 the Referee shall allow the recovery time permitted in Rule 16.3.3.1 Such an injury could be the result of a blow, especially to the face or head, as a result of the player colliding with the walls or floor, or a possible muscle tear or sprained joint causing the player to stop suddenly. 
It is the responsibility of the injured player to be back at the court when the Referee calls "Time", either to resume play, or to request an extension of recovery time, if required, in the case of an injury which is still bleeding. If the player is not present when "Time" is called the Referee shall award the match to the opponent. 
The player shall make the decision to resume play. The Referee's role is to decide whether an injury exists, to apply and monitor time-intervals and to apply the Rules when the total allocated recovery time has elapsed.
G15 Coaching
Coaching of players is permitted only during the interval between games. Coaching does not include brief comments of encouragement between rallies that clearly have no effect on the continuity of play. The Referee shall decide whether comments are permissible encouragement or improper coaching. 
The use of external communication aids is prohibited. 
The Referee may penalise coaching in any form during play by applying Rule 17 to the player being coached.
G16 Progression of penalties
The penalties available to the Referee under Rule 17 are: Warning (called a Conduct Warning). 
Stroke awarded to opponent (called a Conduct Stroke). 
Game awarded to opponent (called a Conduct Game). Match awarded to opponent (called a Conduct Match). 
The guidelines for applying the penalties are as follows: 
When the Referee imposes the first penalty for a particular offence, it should be a warning, stroke, game or match depending on the seriousness of the offence. However, any subsequent penalty for the same type of offence for the same player should not be less severe than the previous penalty for that offence. Thus the Referee may award more than one warning or stroke for the same type of offence if the Referee decides that the offence does not warrant a more severe penalty. 
When issuing penalties the Referee shall use the following terminology: Conduct warning (player or team's name) for(Offence). 
Conduct stroke (player or team's name) for (Offence), stroke to (opponent or opposing team's name). Conduct game (player or team's name) for (Offence), game to (opponent or opposing team's name). Conduct match (player or team's name) for (Offence), match to (opponent or opposing team's name). 
The Marker shall repeat only that part of the Referee's decision that affects the score.
G17 Single official
If it is not possible to have two Officials for a match, a single Official acts as Marker and Referee. The Official calls the play and the score as Marker and answers appeals as Referee. 
When there is a single Official, the decisions which the Referee normally makes directly - such as when the ball strikes a player or answering appeals under Rule 12 - present no problems. However, there are limitations in the appeals process related to the Marker’s decisions. Specifically a Marker making an affirmative call (e.g. "Out") is unlikely, as Referee, to reverse that decision on appeal. On the other hand, in the event of the Marker’s failure to call (e.g. a suspected service fault) an appeal may be worthwhile because the Referee's response shall be either "Good" or "Uncertain". In the latter case the Referee shall allow a let.
G18 Markers Guidelines
The Marker shall call services and returns that are not good as soon as they occur using the appropriate call, thereby stopping the rally. 
The correct order of calls is: 1. Anything affecting the score. 2. The score with the server's score always called first. 3. Comments on the score: 
Examples are: 
"Not up, hand-out, 4-3." 
"Down, 10-all, player must win by two points." "Out, 10-all, player must win by two points." 
"Yes let, 3-4." 
"No let, hand-out, 5-7." 
"Stroke to Jones, 10-2, match ball." "Foot fault, hand-out, 1-0." 
"Fault" (appeal by server, Referee uncertain). "Yes let, 10-3, game ball." 
Match introduction: 
"Smith serving, Jones receiving, best of 5 games, love-all." 
End of a game: 
"11-7, game to Smith. Smith leads one game to love." "12-10, game to Smith. Smith leads two games to love." "11-3, game to Jones. Smith leads two games to one." "11-4, game to Jones, two games all." 
"12-10, match to Smith, 11-7, 12-10, 3-11, 4-11, 12-10." 
Start of subsequent game: 
"Smith leads one game to love, love-all." 
"Smith leads two games to one, Jones to serve, Love-all" 
"Two games all, Smith to serve, love-all." 
After award of Conduct penalty: "Stroke to Smith, 7-2". 
"11-7, game to Jones, two games all".
G19 Referee's Guideline
Addressing the players: Officials should use the player’s surname/family name, rather than the given name, when addressing players. This eliminates any appearance of familiarity that players or spectators could interpret as favouritism. 
Explanations: Following an appeal by a player, the Referee normally gives the decision and play resumes. However, on some occasions, it may be appropriate to explain the decision to the players. In those cases the Referee may give a concise explanation following the decision. It is helpful to the players if the Referee uses the terminology of the appropriate rule when explaining a decision.