Horizontal jumps (long jump and triple jump) and all throws must be initiated behind a line. In the case of horizontal jumps, that line is a straight line perpendicular to the runway. In the case of throws, that line is an arc or a circle. Crossing the line while initiating the attempt invalidates the attempt—it becomes a foul. All landings must occur in a sector. For the jumps, that is a sand filled pit, for throws it is a defined sector. A throw landing on the line on the edge of sector is a foul (the inside edge of the line is the outside edge of the sector). Assuming a proper attempt, officials measure the distance from the closest landing point back to the line. The measuring tape is carefully straightened to the shortest distance between the point and the line. To accomplish this, the tape must be perfectly perpendicular to the take off line in jumps, or is pulled through the center point of the arc for throws. The officials at the landing end of the tape have the zero, while the officials at the point of initiation measure and record the length. Whenever a record (or potential record) occurs, that measurement is taken (again) with a steel tape, and observed by at least three officials (plus usually the meet referee). Steel tapes are easily bent and damaged, so are not used to measure everyday competitions. For major competitions, each competitor gets three tries. The top competitors (usually 8 or 9 depending on that competition's rules or the number of lanes on the track) gets three more tries. At that level of competition, the order of competitors for those final three attempts are set—so the competitor in first place at the end of the third round is last, while the last competitor to qualify goes first. Some meets rearrange the competition order again for the final round, so the final attempt is taken by the leader at that point. At other competitions, meet management may choose to limit all competitors to four or three attempts. Whatever the format, all competitors get an equal number of attempts.