stumpings, doubtful catches and whether the ball has crossed the boundary for a six or short of a four. The International Cricket Council decided to trial a referral system during the Indian tour of Sri Lanka through late July and August 2008. This new referral system allows players to seek reviews, by the third umpire, of decisions by the on-field umpires on whether or not a batsman has been dismissed. Each team can make two unsuccessful requests per innings, which must be made within a few seconds of the ball becoming dead; once made, the requests cannot be withdrawn. Only the batsman involved in a dismissal can ask for a review of an "out" decision; in a "not out", only the captain or acting captain of the fielding team. In both cases players can consult on-field teammates but signals from off the field are not permitted. A review request can be made by the player with a 'T' sign; the umpire will consult the TV umpire, who will review TV coverage of the incident before relaying back fact-based information. The field umpire can then either reverse his decision or stand by it; he indicates "out" with a raised finger and "not out" by crossing his hands in a horizontal position side to side in front and above his waist three times. The TV umpire can use regular slow-motion, or high-speed camera angles usually called ultra-motion or super-slow replays, the mat, sound from the stump mics and approved ball tracking technology, which refers to Hawk-Eye technology that would only show the TV umpire where the ball pitched and where it hit the batsman's leg and it is not to be used for predicting the height or the direction of the ball. Snicko and Hot Spot can also be used. Fencing Video-refereeing is compulsory at World Championships, Grand Prix competitions and at the Olympic Games, and is used when the referee cannot decide if a touch is to be awarded, at request of a player (although only two incorrect video appeals are allowed per player in individual competitions) or if the score is tied in the last point and both lights turn on. There is an assistant official, called "video-referee", who is watching the live match and helps the referee on the decision through a slow motion replay on a monitor close to the piste. It is specially used to decide the