one fewer opportunity to kill clock time in the Canadian game with three downs, and can only take the play clock time (20 seconds) and the length of the play itself off the clock with each down. On the other hand, Canadian teams only receive one timeout per half, as opposed to three in American football. After the three-minute warning, a penalty of a loss of down (on first and second down, 10 yards on third down) results for failing to start the new play in time (time count violation). Additionally, if a Canadian team commits a time count violation on third down, the referee has the right to require that it legally start a new play before the play clock expires, and can award possession to the defending team if another time count is committed. Moreover, in any quarter, when the game clock expires while the ball is dead in Canadian football, a final play must be run with "zeros on the clock" before the quarter ends, whereas in American football the expiration of time while the ball is dead immediately ends the quarter (including overtime periods in such cases where those periods are timed). In American football, it is common (or even, arguably, expected) for teams including coaching staffs and other such personnel to come on the field in order to shake hands, etc. before the game clock officially expires, especially in cases where the trailing team does not have possession of the ball, has no timeouts left and the result of the final play of the game left the clock running with less than forty seconds left. The main caveats are that in all gridiron codes, a half cannot end on any penalty accepted by the non-penalized team even if there is no time remaining on the clock, and a team may always elect to attempt a conversion after a touchdown even if time is expired, so it is always possible for a final play to run with "zeros on the clock" under such circumstances. If a team that is trailing in the CFL can begin to produce two-and-outs on defense and efficient scoring drives on offense, 14 and even 17 points can be successfully scored in the final three minutes. This comeback proclivity is so pronounced that the CFL uses it for marketing purposes: No Lead Is Safe. See also American football American football rules Glossary