Rule 4.02

Rule 4.02
The players of the home team shall take their defensive positions, the first batter of the visiting team shall take his position in the batter's box, the umpire shall call “Play” and the game shall start.


DISCUSSION
Until Rule 4.02 became part of the rulebook in 1950, the home team captain could decide to bat either first or last, and batted last as a matter of tradition.


Remember, the umpire calls "Play," not "Play Ball!"