To ensure competition is fair and equal, all Paralympic sports have a system in place which ensures that winning is determined by skill, fitness, power, endurance, tactical ability and mental focus, the same factors that account for success in sport for able bodied athletes.This process is called classification and its purpose is to minimise the impact of impairments on the activity (sport discipline). Having the impairment thus is not sufficient. The impact on the sport must be proved, and in each Paralympic sport, the criteria of grouping athletes by the degree of activity limitation resulting from the impairment are named ‘Sport Classes’. Through classification, it is determined which athletes are eligible to compete in a sport and how athletes are grouped together for competition. This, to a certain extent, is similar to grouping athletes by age, gender or weight.Classification is sport-specific because an impairment affects the ability to perform in different sports to a different extent. As a consequence, an athlete may meet the criteria in one sport, but may not meet the criteria in another sport.Nordic Skiing ClassificationSkiers in Cross-Country and Biathlon compete in several different sport classes, depending on the activity limitation that their impairment causes.Sport Classes LW 2-9: Standing SkiersSkiers with leg impairments:Sport Class LW 2: The skiers have an impairment affecting one leg, for example an amputation above the knee. They will use a prosthesis and ski with two skis.Sport Class LW 3: This sport class includes skiers with an impairment in both legs, such as muscle weakness in both legs.Sport Class LW 4: Skiers in this sport class include those with impairments in the lower parts of one leg, but with less impact on skiing compared to LW 2. Typical examples are amputations above the ankle or loss of muscle control in one leg.Skiers with arm impairments:Sport Class LW 5/7: This sport class is designated for athletes with impairments in both arms that prohibit them to use ski poles. Skiers, for example, have no hands or cannot grip firmly. Therefore, you will see them skiing without poles.Sport Class LW 6: Athletes competing in the LW 6 sport class have a significant impairment in one arm, for example a missing arm above the elbow. The impaired arm is fixed to their body and may not be used during the races. With the other hand they will use a ski pole.Sport Class LW 8: Skiers in this sport class have moderate impairments affecting one arm. Athletes, for example, cannot flex the elbow or fingers on one side or they have a below elbow amputation. They will use one ski pole only.Skiers with combined impairments in arms and legs:Sport Class LW 9: This sport class is designed for skiers who have an impairment in arms and legs. Some of the LW9 skiers have mild coordination problems in all extremities. Others have amputations affecting at one arm and one leg. Depending on their abilities, they will ski with one or two ski poles.Sport Classes LW 10-12: Sit-SkiersAll sit-skiers have an impairment affecting their legs. They are allocated different sport classes depending on their trunk control, which is very important for acceleration and balancing during the races.Sport Class LW 10: Skiers have an impairment that limits their leg and trunk function. They would be unable to sit without supporting himself or herself with the arms, for example due to paraplegia.Sport Class LW 10.5: Skiers in this sport class also have limited trunk control, but they can keep their sitting balance when not moving sideways. Sport Class LW 11: Skiers have a leg impairment and fair trunk control, which enables them to balance even when moving sideways. Sport Class LW 11.5: Skiers in this sport class have near to normal trunk control.Sport Class LW 12: Skiers in this sport class have impairments similar to those described for the sport classes LW 2-4: They have a leg impairment, but normal trunk control. They are eligible to compete standing or sitting and can chose their preferred way of skiing at their first Classification. Sport Classes B1-3: Skiers with visual impairmentSport Class B1: Skiers in this sport class are either blind or have very low visual acuity. By way of explanation, their level of visual acuity is such that the athlete cannot recognize the letter “E” (15x15cm in size) from a distance of 25cm. During the race they wear eyeshades. Sport Class B2: This sport class profile includes athletes with a higher visual acuity than athletes competing in the B1 class, but they are unable to recognize the letter “E” from a distance of 4m. Moreover, athletes with a visual field of less than 10 degrees diameter are eligible for this sport class.Sport Class B3: The B3 sport class profile describes the least severe visual impairment eligible for Nordic Skiing. Eligible athletes either have a restricted visual field of less than 40 degrees diameter or a low visual acuity.For B1 skiers a guide is obligatory and B2 and B3 skiers may choose to ski with a guide. The guide skis immediately ahead of the athlete and verbally informs the athlete of course specifics such as corners, inclines, and declines. In Biathlon, athletes with visual impairment shoot at the target by following sound signals.The Percentage System in Nordic SkiingThe percentage-system is an adjusted time formula, which is used to determine overall place of each competitor relative to all other racers. This formula assigns a percentage to each competitor based on each individual's particular race class. The athlete’s actual time is multiplied by this percentage to determine his/her adjusted finishing time. Each class has different percentage for the different techniques, classic and free technique. The percentages will be evaluated after every season and changes will be done if necessary. This will be done by the IPNSC.