Classification Figure for International Sitting Volleyball. Adapted from Volleyball Canada 
Players are assigned a classification of either minimally disabled (MD) or disabled (D; also known as full disabled). Classification is conducted using one or more of the following measures: muscle strength, amputation level, range of motion of multiple joints, limb paralysis, and differences in limb length. In general, athletes with a disability tend to have major acquired or congenital impairments, including any impairment that can affect an individual’s body control. Minimally disabled athletes generally are unable to play able-bodied volleyball due to long-term chronic injuries .
For international sitting volleyball competitions, teams may only have two minimally disabled players on the roster and only one minimally disabled player on the court at any given time. The six players on the court must fulfill this requirement at all times, even when a Libero is on the court. A full roster consists of a total of 12 players, with 6 players allowed on the court at any given time .
Similar to standing volleyball, sitting volleyball involves playing a total of 5 sets to 25 points each using rally scoring with a minimum lead of two points needed to win the set. The match is won by the team who wins three sets. In some domestic and club tournaments, however, the winner is the best of three sets. In the case of a 2-2 tie, the deciding fifth set is played to 15 points with a minimum lead of two points needed to win the set. In order to put the ball into play, a serve is sent into the opponent’s court over the net by the server. The basic pass-set-spike combinations are essential in all versions of the sport.
Despite the general principles being similar, there are some differences in sitting volleyball as compared with standing volleyball. First, when striking a ball, part of the player’s torso (measured from buttocks to shoulders) must remain in contact with the ground. Second, a player’s legs may cross the service, attack, and center lines as long as there is no interference with an opposing player. Third, blocking or attacking a serve is legal in sitting volleyball. The pace of sitting volleyball at the competitive level is noted to be as fast as or faster than that of standing volleyball.
Special Positions 
Before the match, the coach records and/or checks the names and numbers of the players on the score sheet and then signs the score sheet. During the match, the coach provides the second referee or scorer with their lineup sheet. The coach also requests time-outs and substitutions and may give instructions to players while in the free zone in front of the team bench without interrupting or delaying the match. In World ParaVolley Official Competitions and Zonal Championships, a coach’s restriction line is added and the coach may only perform his/her function behind this line.
The role of the assistant coach is to assume the coach’s function during a coach’s absence once approved by the referee. The assistant coach sits on the team bench but may not intervene in the match in any way.
Team Leader (Captain)
Before the match, the team captain is responsible for signing the score sheet and representing his/her team in the coin toss. During the match, the captain may speak to the referees for interpretation of game plays, to ask for authorization to change or check equipment, and in the absence of the coach, to ask for time-outs and substitutions. The team captain signs the score sheet again at the end of the match to endorse the final result and has the right to record an official protest regarding the referee’s application or interpretation of the rules during the match.
At the start of the match, each team may designate up to two Liberos who act as defensive specialists. Only one Libero is allowed on the court at any time. The Libero may replace any of the players in a back-row position and is not allowed to complete an attack hit from anywhere if at the moment of contact the ball is entirely above the net. He/she may not serve, set in the front row, block, or attempt to block. Libero replacements are not counted as substitutions and are unlimited. The Libero must wear a uniform, jacket, or bib of a different dominant color from the color of the rest of the team, and it must clearly contrast with the rest of the team’s uniforms. These rules are similar to that of traditional volleyball.
The playing court and the free zone around the court should be rectangular and symmetrical. The playing court itself measures 10 m × 6 m and is surrounded by a 3 m free zone on all sides (Figs. 20.2 and 20.3). A free playing space above the playing area should be free from any obstructions and be at least 7 m above the playing surface. The court is surrounded by boundary lines that are 5 cm wide and of a light color that is different from the court.
Playing Area Dimensions, simplified. Adapted from National Center on Health, Physical Activity and Disability 
WordPress theme by UFO themes