(a) A regulation game consists of nine innings, unless extended because of a tie score, or shortened (1) because the home team needs none of its half of the ninth inning or only a fraction of it, or (2) because the umpire-in-chief calls the game.
EXCEPTION: National Association leagues may adopt a rule providing that one or both games of a double-header shall be seven innings in length. In such games, any of these rules applying to the ninth inning shall apply to the seventh inning.
(b) If the score is tied after nine completed innings play shall continue until (1) the visiting team has scored more total runs than the home team at the end of a completed inning, or (2) the home team scores the winning run in an uncompleted inning.
(c) If a game is called, it is a regulation game:
(1) If five innings have been completed;
(2) If the home team has scored more runs in four or four and a fraction half-innings than the visiting team has scored in five completed half-innings;
(3) If the home team scores one or more runs in its half of the fifth inning to tie the score.
(d) If a regulation game is called with the score tied, it shall become a suspended game. See Rule 7.02 (Rule 4.12).
(e) If a game is postponed or otherwise called before it has become a regulation game, the umpire-in-chief shall declare it “No Game,” unless the game is called pursuant to Rules 7.02(a)(3) or 7.02(a)(4) (Rules 4.12(a)(3) or 4.12(a)(4)), which shall be a suspended game at any time after it starts.
(f) A League President may determine whether rain checks will be honored for any regulation or suspended game that has progressed to or beyond a point of play described in Rule 7.01(c) (Rule 4.10(c)).
Rule 7.01 Comment (Rule 4.10 Comment): The Major Leagues have determined that Rules 7.01(c) and 7.01(e) (Rules 4.10(c) and 4.10(e)) do not apply to any Wild Card, Division Series, League Championship Series or World Series games or for any additional Major League championship season game played to break a tie.
(g) (4.11) The score of a regulation game is the total number of runs scored by each team at the moment the game ends.
(1) The game ends when the visiting team completes its half of the ninth inning if the home team is ahead.
(2) The game ends when the ninth inning is completed, if the visiting team is ahead.
(3) If the home team scores the winning run in its half of the ninth inning (or its half of an extra inning after a tie), the game ends immediately when the winning run is scored.
EXCEPTION: If the last batter in a game hits a home run out of the playing field, the batter-runner and all runners on base are permitted to score, in accordance with the base-running rules, and the game ends when the batter-runner touches home plate.
APPROVED RULING: The batter hits a home run out of the playing field to win the game in the last half of the ninth or an extra inning, but is called out for passing a preceding runner. The game ends immediately when the winning run is scored, unless there are two out and the winning run has not yet reached home plate when the runner passes another, in which case the inning is over and only those runs that scored before the runner passes another shall count.
(4) A called game ends at the moment the umpire terminates play, unless it becomes a suspended game pursuant to (Rule 7.02(a) (Rule (4.12(a)).