The systems, which include four-team, five-team, six-team and eight-team variants, were developed by Australian lawyer, historian and English lecturer Ken McIntyre, with the first system developed for the Victorian Football League in 1931.
Most Australian rules football leagues, from professional down to suburban, use a McIntyre finals system.
It was also used in the A-League (soccer) before that competition expanded its finals series to a top-six format.
Under the name Page playoff system, the McIntyre final four is commonly used in softball and curling events, especially in Canada.
The lowest-two-ranked teams play each other, and the winner advances to the preliminary final.
In this system, the top two teams are able to lose a match and still qualify for the grand final, this is referred to as a 'double chance'.
Under this system the top two teams receive a double chance, as does the winner of match B.