The designated player According to the International Softball Federation Playing Rules Committee There can be a 10th player in the lineup known as the designated player This designated player can hit for one of the players on the team He or she is also known as the designated hitter This player is also known as the flex player The flex player can sub in and out for other players on the team Offical Rules of Softball Offical Rules of Softball International Softball Federation Playing Rules Committee 2013 Web 2014