Rule Refresher: Wait What Did that Bell Mean?

Nothing strikes panic in the heart of eventers like trotting through the ring only to hear ding ding. So many thoughts run through your head: "Was that bell for me? Why did they ring the bell?" Check out all of the reasons why you might hear the sound of a bell while you are competing below.
Text has been taken directly from the USEF Rules for Eventing with emphasis added by the USEA.
EV145 The Bell
1. The bell (or other sound) is used to communicate with the competitors. One of the members of the Ground Jury or the additional judge is in charge of the bell and responsible for its use. The bell is used:
a. To give permission to the competitors to enter the arena when the course is ready for their inspection and to signal that the inspection time is over;
b. To give the signal to start and to activate a 45 seconds countdown. The 45 seconds countdown sets the time that the competitor can spare before commencing his round. The Ground Jury has the right to interrupt the 45-second countdown if unforeseen circumstances occur. Disobediences, falls, etc., occurring between the signal to start and the moment the competitor crosses the starting line in the correct direction, are not penalized. After the bell has rung, crossing the starting line in the correct direction for a second time before jumping the first obstacle is counted as disobedience;
c. To stop a competitor for any reason or following an unforeseen incident and to signal to him to continue his round after an interruption (EV152.9a);
d. to indicate to him that an obstacle knocked down, following a disobedience, has been replaced (EV152.9a);
e. To indicate by prolonged and repeated ringing that the competitor has been eliminated.
2. If the competitor does not obey the signal to stop, he may be eliminated at the discretion of the Ground Jury (EV154.3d) except where specifically provided for under EV152.9b
3. If, after an interruption, the competitor restarts and jumps or attempts to jump without waiting for the bell to ring, he will be eliminated (EV154.2m)
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