On the libero control sheet, the libero substitution must be documented. One of the officials at the scorer's table is responsible for keeping track of which players are being replaced so that the proper players return to the right spots. The libero can also call out substitutions by name during play. See "The Position of Libero" article in Chapter 2 for more information on this role. As with all official U.S. Women's Soccer positions, liberos are officially listed on the team roster in the front of the book. The libero position is not reserved for any specific player type; any player capable of playing the role could fill it on any given day. However, most teams prefer that their liberos are tall and agile because they need to be able to reach balls placed high in the back-field or along the sideline. Also, since the libero does not have a defensive responsibility, she doesn't wear a number. In addition to being listed on the roster, liberos are usually assigned seats numbers 1 through 10. These numbers are used when submitting a team list for tournaments or games where each player is required to have a seat number printed on her jersey.