<Li> The bat may be made of wood, or a composite material that meets NCAA standards . Since the 2011 season, composite bats have been required to pass the "Bat - Ball Coefficient of Restitution" (BBCOR) test . </Li> <Li> The designated hitter rule is used . In addition, a player may serve as both pitcher and DH at the same time and may remain in one position when removed in the other . </Li> <Li> One or both ends of a doubleheader are sometimes seven innings in length . However, the NCAA has recently tightened the interpretation of what constitutes a regulation game, encouraging schools to play as many nine - inning games as possible . Seven - inning games may be played on the final day of a conference series, or if the two teams in a non-conference match will play two games in one day, often to make up a game that could not be played earlier in the year due to inclement weather . </Li> <Li> A mercy rule may be in use, which terminates play when one team is ahead by 10 or more runs after seven innings (61⁄2 innings if the home team is winning). In games that are scheduled for seven innings the rule takes effect in the fifth . This rule is not used in NCAA tournament games . Several conferences institute this rule only on Sundays or the final day of a conference series so that the visiting team can travel early . In some conferences, the mercy rule may also be used to end such games in order to start the next tournament game sooner . </Li>

How many innings in college baseball world series
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