Generally, tracks are laid, marked, and mapped on the day previous to the tracking trial by the trial judge or steward. Tracks are chosen so that the judge or steward can easily determine where the track is located, and where articles are to be placed, even after the marks, ribbons, or flags have been removed. The length of the track, the number of corners, the number of articles left on the track depends on the level of difficulty of the track and the rules of the organization under which the trial is being run.