The Canadian Olympic Curling Trials, known as the Tim Hortons Roar of the Rings since 2005 for sponsorship reasons, occur every four years, in the year preceding the Winter Olympic Games. They are held to determine the men's and women's representatives at the next year's Olympic Games. The system of qualification for the Curling Trials varies for each event, and can be quite complicated. One main reason for an Olympic qualifying event apart from the national championships (The Brier and the Scotties) is that provincial residency rules do not apply to the Olympic team. Curling was added to the Olympic programme in 1998, and a Canadian Olympic Trials have been held the year prior since 1997.