GGS clock can be specified in the following way: [ini[,[N]m1]]/[inc[,[N]m2]]/[ext[,[N]m3]] where ini, inc and ext are times specified in [[HH:]MM:]SS format. Clock parameters have following meaning: Initial time (ini) is the time during which player has to make m1 moves. If m1 is 0, player has to complete the whole game in ini time. Parameter N specifies what happens if the player does not complete game or m1 moves during ini period. If N is not present, clock goes into soft-timeout loss[1]. If N (read NOT loss) is present, clock goes into overtime (extension time) mode. Completion of m1 moves causes clock to go to overtime mode too. In overtime mode, player has to make m3 moves during overtime period. If m3 is 0, player has to complete the whole game. Parameter N specifies how is overtime added to the clock. If N is not present, overtime is additive, i.e. it is added to the remaining time. if N (read NOT add) is present, clock is set to overtime, any unused time is lost. If player does not complete game or m3 moves during ext period, clock goes into hard-timeout[2]. Increment time (inc) is the time that will be added to players clock every m2 moves (m2 >= 1). Parameter N specifies how is increment time added to the clock. If N is not present, increment time is additive, i.e. it is added to remaining time. If N (read NOT additive) is present, min( spent_time, increment_time ) is added to the clock. See formula page to see how to access clock parameters in a formula. Footnotes: [1] Some games, like Othello have soft-timeout, it ensures minimal loss, but player is allowed extension time to complete the game. The actual score is min( minimal_loss, board_score ). Other (mostly win/draw/loss) games treat soft-timeout as hard-timeout. [2] Hard-timeout results in maximal loss. Here are few examples that ilustrate clock specifications: Chess tournament clock: 2 hours for 40 minutes, if the game is not finished, players receive additional 30 minutes to complete the game: 2:00:00,40//30:00,0 Blitz chess, Fisher clock: 2 minutes plus 12 seconds per move: 2:00,0/12/0 Blitz chess, Bronstein clock: 2 minutes, at most 12 seconds per move: 2:00,0/12,N1/0 Othello tournament clock: 30 minutes to complete the game, 2 minutes to complete the lost game in the case of timeout: 30:00,0//2:00,0 Go tournament clock: 30 minute to complete the game, if the game is not finished, player receives 5 minutes overtime for 10 moves: 30:00,N0//5:00,N10