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When claiming a tile for kong, pung or chow the player first calls “kong”, “pung” or “chow” clearly, The calls “kan”, “pon” or “chi” are equally valid. Secondly the player reveals the matching tiles from the hand and thirdly discards a tile from the hand and claim the tile called for. For the third step the order of the two actions is not important: the player can take the claimed tile first and then discard, or the other way round.
Errors in the order above when claiming tiles should be pointed out to the player, but there will be no penalty.

While a player who claims a tile can make a discard before placing the claimed tile with his revealed tiles, the player should take the tile before the next two players have made a discard. Failing to take the tile in a timely manner results in a dead hand, since the player will have a false set.

Empty calls for kong, pung or chow (calling kong, pung or chow and regretting it immediately before revealing any tiles) are not penalized.
Empty calls for ron or tsumo (calling ron, tsumo or mahjong, but not showing the tiles before realising the mistake) results in a dead hand.
A player must use a valid term for calling a win. A player calling “Ippatsu” and revealing his tiles is subject to chombo penalty. A player immediately correcting an invalid term, e.g. “Hu – I mean tsumo” or “Ippatsu – I mean ron” have a valid hand. Players confusing the terms “ron” and “tsumo” have a valid hand, but it should be pointed out that a valid term should be used and repeated offenses of this type are subject to further penalty at the referee’s discretion.

Calls are not supposed to be changed. The first call should be the valid one. However, unless the call was for winning, a quick correction is allowed.
A player calling “pung, no ron” has made a valid correction of his call, and the ron call is valid.
A player calling “ron, no pung” has made a call for winning.The player can claim the tile for ron, but not for pung. If he doesn't have a winning hand, he has a dead hand if no tiles were revealed or if two tiles for the pung call was revealed. If the player has revealed all his tiles in this case, he receives a chombo penalty.

If a player claims a false sets, e.g.
 
it can be corrected if it is discovered before the player discards a tile. After the discard, the mistake cannot be corrected, resulting in a dead hand.

Exposing a few tiles is not penalized. Exposed tiles are placed back in the wall or in the hand where they came from.

Exposing tiles during the deal is not penalized. If the situation is judged problematic for the game play there is a re-deal, but no penalties.

If too many tiles are exposed during the game, play cannot continue. This is a judgment that depends on the circumstances and the progression of the game. As a rule of thumb, play cannot continue if a large fraction of the wall is destroyed or several tiles revealed from an opponent’s hand. If the game cannot continue, the offending player receives a chombo penalty. If the mistake happened due to no mistake on a player’s part, there is a re-deal (like chombo, but without any point penalty).

After the hand ends, players should not expose tiles from the wall or the dead wall.

Tiles exposed on purpose in severe or repeated cases is considered obstruction.

If a player draws a tile from the wrong part of the wall, and the mistake is realised or pointed out before the discard, the mistake should be corrected. After the discard the error cannot be corrected. In either case there is no penalty.

A valid riichi declaration should be announced in three steps: first the players clearly calls “riichi”, secondly the player discards a tile and rotates it sideways in the discard line, e.g.

and thirdly the player places a 1000 point stick on the table close to his discards and close to the center of the table where it is clearly visible to all opponents. A player who completes the first two steps, but forgets to place the riichi bet of 1000 points still has a valid riichi, but should correct the mistake as soon as it is realised or pointed out. Opponents should point out the mistake. A player who fails to call “riichi” or fails to rotate the discard has not made a valid riichi declaration. The riichi bet is returned and the player has a dead hand.
If an opponent claims the rotated tile for a melded set, and the player forgets to rotate the next discarded tile, opponents should point out and the mistake. There is no penalty.
Attempting to declare riichi on a open hand results in a dead hand.

Passing information or hints on opponents’ strategy in any way, e.g. on tenpai status, whether discards are dangerous or what yaku someone might be aiming for is bad behaviour and in serious or repeated cases the player is subject to dead hand or point penalties at the referee’s discretion. Normally the opponents should give the offending player a clear warning and in serious or repeated cases call a referee who can choose to penalize the player.
It is permissible to correct a player who is about to commit a minor irregularity or etiquette error, e.g. drawing a tile from the wrong place in the wall, claiming a false set or forgetting to take a replacement tile.
It is permissible to make it clear if a player has a dead hand, e.g. too many or too few tiles.

Cheating and obstruction are disruptive disturbances of a tournament and deliberate disturbances should be punished hard. Players should enact fair play and not abuse the rules or exploit loop-holes.
A player caught cheating should be immediately disqualified; but it is a very serious accusation so the evidence must be clear.
Deliberate obstructive behaviour is penalized at the referee’s discretion with point penalties of 8000 or 12,000 points (chombo level), or in serious or repeated cases with point penalties between 12,000 and 48,000. These point penlties are deducted from the player’s score at the end of the game after uma is added, thus not affecting ranking at the table. The points are not added to the other players’s scores. Further repeated obstructive behaviour results in immediate disqualification.

Players and spectators should have their telephones in silent and non-vibrating mode during play sessions. Depending on the level of disturbance a player is subject to point penalties at the referee’s discretion for a telephone ringing or making other disturbing noises. A player with a specific and important reason for expecting a call should make an agreement with the referee before the session about how to handle the situation.

A player who is late by 10 minutes or less is subject to a point deduction of 1000 points per minute he is late. Thus a player who is 1 minute late has 1000 points deducted from his score, while a player who is 10 minutes late has 10,000 points deducted from his score. These point penlties are deducted from the player’s score at the end of the game after uma is added, thus not affecting ranking at the table. The points are not added to the other players’s scores.
A player who is late by more than 10 minutes is replaced by a substitute player.

If it is clear to the organizers that a player won’t be able to play, e.g. due to illness, a substitute player will take his place.
Substitute players’ session results will always be entered in the tournament score keeping as -15,000 points and -15,000 uma, i.e. a total of -30,000.
However, at the table the substitute’s score will count for determining the opponents’s uma if the substitute played from the beginning of the session (also if the substitution was due to more than 10 minutes lateness). E.g. if the substitute wins the table, the other players will get umas of 5,000, -5,000 and -15,000. So when entering the results, two players will have uma of -15,000 and no one will have the winner uma of 15,000 in this case.
Substitute players who are substituted after the playing has begun at the table (e.g. if a player falls ill during the session, or in case a player is disqualified), will always receive the -15,000 uma, meaning that the other three players will get the 15,000, 5,000 and -5,000 uma even if the substitute scored the most point at the table. This is only the case in the session where the substitution occurs after play has begun. In later sessions, the substitute will play from the beginning of the sessions, and the substitutes result will count when determining the opponent’s umas.
A disqualified player will be ranked at the bottom of the result list and the result will count for the EMA ranking list.
A player who was substituted will receive -15,000 points plus an uma of -15,000 points for each session missed. In case of acceptable reasons like illness the head referee and the tournament organizers may decide to remove the player’s name from the final results, so that it will not count for the player’s EMA ranking.

In tournaments it is convenient to play session on time limits. Often session are scheduled at 90 minutes. When playing with time limited sessions, a clear sound must indicate when 15 minutes remain. After the sound the current hand is finished, and one more hand is played (unless a full game is already completed). There is no sound at 90 minutes; the players should be able to finish the last one or two hands within the remaining time, but if that is not the case they will play until the hands are finished.
A hand begins when the dice are thrown after the walls have been built. If the dice have not been thrown yet when the time signal sounds, the players will play only the current hand. If the dice have just been thrown, the players would get to play two hands. In case of chombo there is a complete redeal, i.e. it does not count as a hand played. A hand that ends in an abortive draw, counts as a hand played.
At the beginning of sessions, waiting for the signal to begin, players are allowed to build the walls, but the dice cannot be thrown and the deal cannot begin before the signal.