Sealing a move
When a game is adjourned, one of the players marks his next move on the game record and seals the record in an envelope. This is called "sealing the move".
If a game is interrupted for a long time, for example to be continued on the next day, then one of the players would have an unfair time advantage of having the whole night to think about his next move, while other player would have to plan for all of the opponent's possible moves.
To remedy this, one of the players decides his move while his clock is running, but does not reveal it to the other player until the game is resumed and the other player's clock is running again.
The player who sealed his move cannot change his mind after the move is sealed. This places both players in the position of "having played last" for the duration of the break.
The European general tournament rules define the following procedure for sealing a move:
At the start of the tournament, the tournament director publishes a list of possible times for adjournment and its maximal duration. At the beginning of a move, a player may adjourn a game by stating that the move is to be sealed. A referee may supervise the process.
The player may "seal" the move by playing the move and neutralising the clock, or the player may fill in a sealing form. If a sealing form is used, then the procedure to be followed is:
- The opponent should begin filling in the form while the player is thinking about the move to seal.
- Once the player has decided on the move, the clock is neutralised.
- The players then promptly complete the sealing form data.
- Without delay, the player clearly marks the move on the form so that the opponent cannot see its location.
- The player seals the form in an envelope.
- The players record the board number, pairing, and time of resumption on the envelope.
- Both players depart from the room, depositing the envelope as required by the tournament organizers.
When the game is to be resumed, the sealing envelope is retrieved (in more important tournaments they are typically stored in a safe) and opened, and the board position is recreated and verified. The sealed move is then played on the board, and the opponent's clock is started.