minute, they start the following move in the second rather than the first byo-yomi period. In effect, the player has one minute per move plus four extra one-minute packets which may be used as needed, e.g. four moves of two minutes each, or one move of five minutes, or any other combination. In higher-level tournaments, such as the Kisei tournament, the player's time is often composed entirely of byo-yomi periods (for example, in an eight-hour game, the player may have 480 periods of one minute each), rather than having a main block of thinking time. In this case, the actual counting of time (verbally) begins once the player falls below a certain threshold of time, such as 10 minutes; when the time is being counted, the player is informed at intervals how much time they have used in their current period, and how many extra periods they have left. (For example, the time may be called at 10-second intervals, and when 55 and 58 seconds have been used; during a player's final minute, the last 10 seconds are counted one by one.) Similarly, in the televised NHK Cup tournament, the player has 30 seconds per move plus 10 extra one-minute periods which may be used as needed. When analog game clocks are used to enforce byo-yomi, it is more convenient to assign additional time for a block of moves, rather than for each move. In Canadian byo-yomi, a player typically gets 5 minutes for 10 to 20 moves. The IGS Go server uses a similar system, but the byo-yomi time is variable and always covers 25 moves. Thus the time control "20 minutes + 15 minutes byoyomi" on IGS means that after the initial 20 minutes of thinking time are over, a player is granted 15 additional minutes, which may be spent however they choose. If these minutes expire before they have made 25 more moves, they lose. If they make 25 more moves in less than 15 minutes, they are granted another 15 minutes of byo-yomi, and so on indefinitely. Canadian byo-yomi imposes a certain average speed of play, but allows the player to spend more time to ponder on difficult moves. Several byo-yomi periods in one move per period variant (also known as Japanese byo-yomi) serve essentially the same purpose, albeit to a lesser extent. Unused time during one byo-yomi period does not carry forward to future moves.