The ringing of the bell, done by the President, marks the beginning and the end of every event. It should be placed at the centre of the head table together with the gavel.
Note: only the President may ring the bell, and only to mark the start and end of the event. It must never be used for anything else — for example, to get participants' attention.
The one exception is the Handover Ceremony: at the end of that gathering, the bell is rung at the same time by both Presidents (outgoing and incoming).