Section 5: Rules of Play
Pitching. Rule 4.3.3 requires the pitcher's delivery to be an underhand windmill or slingshot motion, with the hand below the hip and the wrist no farther from the body than the elbow, no stop or reversal of the forward motion, and the release and follow-through forward and past the straight line of the body. The pitcher may make only one revolution on the windmill pitch and must take one step with the non-pivot foot simultaneous with release, remaining within the 61.0 cm (24 in.) length of the pitcher's plate (Rule 4.3.3e). The pitcher has 20 seconds to release the next pitch after receiving the ball or the umpire's "Play Ball" (Rule 4.3.3k). A pitcher who pushes off from a spot other than the pitcher's plate (a "crow hop," Rule 4.1.2) or who becomes airborne with both feet before landing and continuously delivering the ball ("leaping," Rule 4.1.4) commits an illegal pitch. Each defensive team is limited to three charged defensive conferences in a seven-inning game under Rule 4.2.1; a fourth or subsequent conference in the same game results in the pitcher being declared an illegal pitcher.
Batting. Rule 5.4.3 defines the strike zone in Fast Pitch as the space over home plate between the bottom of the batter's sternum and the bottom of the batter's kneecap when the batter assumes a natural stance. A batter is out under Rule 5.4.4 after three strikes are called (unless the "dropped third strike" rule of Rule 5.1.46 applies with fewer than two outs and first base unoccupied) and is awarded first base after four called balls (Rule 5.1.1). Rule 5.5.1g defines a home run as a fair batted ball that clears the outfield fence in flight over fair territory, or contacts a fielder's glove or body and continues over the fence in fair territory.
Base running. Under Rule 5.10.1, a runner may legally attempt to steal or advance on a pitch, passed ball, or wild pitch only after the pitcher's non-pivot foot touches the ground during the pitching motion. Rule 5.1.26 defines an infield fly as a fair fly ball, other than a line drive or an attempted bunt, that an infielder can catch with ordinary effort when first and second, or first, second, and third bases, are occupied with fewer than two outs; the batter is automatically out regardless of whether the ball is caught. Rule 5.1.19 (force out) and Rule 5.9 (touching bases in order) govern appeal plays for missed bases or runners leaving too soon on a caught fly ball.