notice to the officials. This replacement does not count against the substitution limit each team is allowed per set, although the libero may be replaced only by the player whom he or she replaced. Most U.S. high schools added the libero position from 2003 to 2005. The modern-day libero often takes on the role of a second setter. When the setter digs the ball, the libero is typically responsible for the second ball and sets to the front row attacker. The libero may function as a setter only under certain restrictions. To make an overhand set, the libero must be standing behind (and not stepping on) the 3-meter line; otherwise, the ball cannot be attacked above the net in front of the 3-meter line. An underhand pass is allowed from any part of the court. The libero is, generally, the most skilled defensive player on the team. There is also a libero tracking sheet, where the referees or officiating team must keep track of whom the libero subs in and out for. Under FIVB (Federation Internationale de Volleyball) rules, two liberos are designated at the beginning of the play, only one of whom can be on the court at any time. Furthermore, a libero is not allowed to serve, according to international rules. NCAA rules for both men and women differ on this point; a 2004 rule change allows the libero to serve, but only in a specific rotation. That is, the libero can only serve for one person, not for all of the people for whom he or she goes in. That rule change was also applied to high school and junior high play soon after. Recent rule changes Other rule changes enacted in 2000 include allowing serves in which the ball touches the net, as long as it goes over the net into the opponents' court. Also, the service area was expanded to allow players to serve from anywhere behind the end line but still within the theoretical extension of the sidelines. Other changes were made to lighten up calls on faults for carries and double-touches, such as allowing multiple contacts by a single player ("double-hits") on a team's first contact provided that they are a part of a single play on the ball. In 2008, the NCAA changed the minimum number of points needed to win any of the first four sets from 30 to 25 for